diff --git a/minio/api.py b/minio/api.py
index fd2d1b0b3..72364774a 100644
--- a/minio/api.py
+++ b/minio/api.py
@@ -402,7 +402,7 @@ def _execute(
             no_body_trace=False,
     ):
         """Execute HTTP request."""
-        region = self._get_region(bucket_name, None)
+        region = self._get_region(bucket_name)
 
         try:
             return self._url_open(
@@ -442,22 +442,12 @@ def _execute(
             )
             raise exc.copy(code, message)
 
-    def _get_region(self, bucket_name, region):
+    def _get_region(self, bucket_name):
         """
         Return region of given bucket either from region cache or set in
         constructor.
         """
 
-        if region:
-            # Error out if region does not match with region passed via
-            # constructor.
-            if self._base_url.region and self._base_url.region != region:
-                raise ValueError(
-                    f"region must be {self._base_url.region}, "
-                    f"but passed {region}"
-                )
-            return region
-
         if self._base_url.region:
             return self._base_url.region
 
@@ -479,7 +469,7 @@ def _get_region(self, bucket_name, region):
         element = ET.fromstring(response.data.decode())
         if not element.text:
             region = "us-east-1"
-        elif element.text == "EU":
+        elif element.text == "EU" and self._base_url.is_aws_host:
             region = "eu-west-1"
         else:
             region = element.text
@@ -566,7 +556,7 @@ def select_object_content(self, bucket_name, object_name, request):
                     print(data.decode())
                 print(result.stats())
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if not isinstance(request, SelectRequest):
             raise ValueError("request must be SelectRequest type")
@@ -600,7 +590,8 @@ def make_bucket(self, bucket_name, location=None, object_lock=False):
             # Create bucket with object-lock feature on specific region.
             client.make_bucket("my-bucket", "eu-west-2", object_lock=True)
         """
-        check_bucket_name(bucket_name, True)
+        check_bucket_name(bucket_name, True,
+                          s3_check=self._base_url.is_aws_host)
         if self._base_url.region:
             # Error out if region does not match with region passed via
             # constructor.
@@ -658,7 +649,7 @@ def bucket_exists(self, bucket_name):
             else:
                 print("my-bucket does not exist")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             self._execute("HEAD", bucket_name)
             return True
@@ -676,7 +667,7 @@ def remove_bucket(self, bucket_name):
         Example::
             client.remove_bucket("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         self._execute("DELETE", bucket_name)
         self._region_map.pop(bucket_name, None)
 
@@ -690,7 +681,7 @@ def get_bucket_policy(self, bucket_name):
         Example::
             policy = client.get_bucket_policy("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         response = self._execute(
             "GET", bucket_name, query_params={"policy": ""},
         )
@@ -705,7 +696,7 @@ def delete_bucket_policy(self, bucket_name):
         Example::
             client.delete_bucket_policy("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         self._execute("DELETE", bucket_name, query_params={"policy": ""})
 
     def set_bucket_policy(self, bucket_name, policy):
@@ -718,7 +709,7 @@ def set_bucket_policy(self, bucket_name, policy):
         Example::
             client.set_bucket_policy("my-bucket", policy)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         is_valid_policy_type(policy)
         self._execute(
             "PUT",
@@ -738,7 +729,7 @@ def get_bucket_notification(self, bucket_name):
         Example::
             config = client.get_bucket_notification("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         response = self._execute(
             "GET", bucket_name, query_params={"notification": ""},
         )
@@ -764,7 +755,7 @@ def set_bucket_notification(self, bucket_name, config):
             )
             client.set_bucket_notification("my-bucket", config)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, NotificationConfig):
             raise ValueError("config must be NotificationConfig type")
         body = marshal(config)
@@ -800,7 +791,7 @@ def set_bucket_encryption(self, bucket_name, config):
                 "my-bucket", SSEConfig(Rule.new_sse_s3_rule()),
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, SSEConfig):
             raise ValueError("config must be SSEConfig type")
         body = marshal(config)
@@ -822,7 +813,7 @@ def get_bucket_encryption(self, bucket_name):
         Example::
             config = client.get_bucket_encryption("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             response = self._execute(
                 "GET",
@@ -844,7 +835,7 @@ def delete_bucket_encryption(self, bucket_name):
         Example::
             client.delete_bucket_encryption("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             self._execute(
                 "DELETE",
@@ -878,7 +869,7 @@ def listen_bucket_notification(self, bucket_name, prefix='', suffix='',
                 for event in events:
                     print(event)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if self._base_url.is_aws_host:
             raise ValueError(
                 "ListenBucketNotification API is not supported in Amazon S3",
@@ -909,7 +900,7 @@ def set_bucket_versioning(self, bucket_name, config):
                 "my-bucket", VersioningConfig(ENABLED),
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, VersioningConfig):
             raise ValueError("config must be VersioningConfig type")
         body = marshal(config)
@@ -932,7 +923,7 @@ def get_bucket_versioning(self, bucket_name):
             config = client.get_bucket_versioning("my-bucket")
             print(config.status)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         response = self._execute(
             "GET",
             bucket_name,
@@ -1033,7 +1024,7 @@ def fget_object(self, bucket_name, object_name, file_path,
                 ssec=SseCustomerKey(b"32byteslongsecretkeymustprovided"),
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if progress and not isinstance(progress, Thread):
             raise TypeError("progress object must be instance of Thread")
@@ -1144,7 +1135,7 @@ def get_object(self, bucket_name, object_name, offset=0, length=0,
                 response.close()
                 response.release_conn()
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         check_ssec(ssec)
 
@@ -1223,7 +1214,7 @@ def copy_object(self, bucket_name, object_name, source,
             )
             print(result.object_name, result.version_id)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if not isinstance(source, CopySource):
             raise ValueError("source must be CopySource type")
@@ -1426,7 +1417,7 @@ def compose_object(  # pylint: disable=too-many-branches
             )
             print(result.object_name, result.version_id)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if not isinstance(sources, (list, tuple)) or not sources:
             raise ValueError("sources must be non-empty list or tuple type")
@@ -1660,7 +1651,7 @@ def put_object(self, bucket_name, object_name, data, length,
                 legal_hold=True,
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         check_sse(sse)
         if tags is not None and not isinstance(tags, Tags):
@@ -1861,7 +1852,7 @@ def stat_object(self, bucket_name, object_name, ssec=None, version_id=None,
             )
         """
 
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         check_ssec(ssec)
 
@@ -1909,7 +1900,7 @@ def remove_object(self, bucket_name, object_name, version_id=None):
                 version_id="dfbd25b3-abec-4184-a4e8-5a35a5c1174d",
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         self._execute(
             "DELETE",
@@ -1985,7 +1976,7 @@ def remove_objects(self, bucket_name, delete_object_list,
             for error in errors:
                 print("error occurred when deleting object", error)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
 
         # turn list like objects into an iterator.
         delete_object_list = itertools.chain(delete_object_list)
@@ -2048,12 +2039,12 @@ def get_presigned_url(self, method, bucket_name, object_name,
             )
             print(url)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if expires.total_seconds() < 1 or expires.total_seconds() > 604800:
             raise ValueError("expires must be between 1 second to 7 days")
 
-        region = self._get_region(bucket_name, None)
+        region = self._get_region(bucket_name)
         query_params = extra_query_params or {}
         query_params.update({"versionId": version_id} if version_id else {})
         query_params.update(response_headers or {})
@@ -2178,9 +2169,11 @@ def presigned_post_policy(self, policy):
             raise ValueError(
                 "anonymous access does not require presigned post form-data",
             )
+        check_bucket_name(
+            policy.bucket_name, s3_check=self._base_url.is_aws_host)
         return policy.form_data(
             self._provider.retrieve(),
-            self._get_region(policy.bucket_name, None),
+            self._get_region(policy.bucket_name),
         )
 
     def delete_bucket_replication(self, bucket_name):
@@ -2192,7 +2185,7 @@ def delete_bucket_replication(self, bucket_name):
         Example::
             client.delete_bucket_replication("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         self._execute("DELETE", bucket_name, query_params={"replication": ""})
 
     def get_bucket_replication(self, bucket_name):
@@ -2205,7 +2198,7 @@ def get_bucket_replication(self, bucket_name):
         Example::
             config = client.get_bucket_replication("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             response = self._execute(
                 "GET", bucket_name, query_params={"replication": ""},
@@ -2248,7 +2241,7 @@ def set_bucket_replication(self, bucket_name, config):
             )
             client.set_bucket_replication("my-bucket", config)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, ReplicationConfig):
             raise ValueError("config must be ReplicationConfig type")
         body = marshal(config)
@@ -2269,7 +2262,7 @@ def delete_bucket_lifecycle(self, bucket_name):
         Example::
             client.delete_bucket_lifecycle("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         self._execute("DELETE", bucket_name, query_params={"lifecycle": ""})
 
     def get_bucket_lifecycle(self, bucket_name):
@@ -2282,7 +2275,7 @@ def get_bucket_lifecycle(self, bucket_name):
         Example::
             config = client.get_bucket_lifecycle("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             response = self._execute(
                 "GET", bucket_name, query_params={"lifecycle": ""},
@@ -2321,7 +2314,7 @@ def set_bucket_lifecycle(self, bucket_name, config):
             )
             client.set_bucket_lifecycle("my-bucket", config)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, LifecycleConfig):
             raise ValueError("config must be LifecycleConfig type")
         body = marshal(config)
@@ -2342,7 +2335,7 @@ def delete_bucket_tags(self, bucket_name):
         Example::
             client.delete_bucket_tags("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         self._execute("DELETE", bucket_name, query_params={"tagging": ""})
 
     def get_bucket_tags(self, bucket_name):
@@ -2355,7 +2348,7 @@ def get_bucket_tags(self, bucket_name):
         Example::
             tags = client.get_bucket_tags("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         try:
             response = self._execute(
                 "GET", bucket_name, query_params={"tagging": ""},
@@ -2380,7 +2373,7 @@ def set_bucket_tags(self, bucket_name, tags):
             tags["User"] = "jsmith"
             client.set_bucket_tags("my-bucket", tags)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(tags, Tags):
             raise ValueError("tags must be Tags type")
         body = marshal(Tagging(tags))
@@ -2403,7 +2396,7 @@ def delete_object_tags(self, bucket_name, object_name, version_id=None):
         Example::
             client.delete_object_tags("my-bucket", "my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         query_params = {"versionId": version_id} if version_id else {}
         query_params["tagging"] = ""
@@ -2426,7 +2419,7 @@ def get_object_tags(self, bucket_name, object_name, version_id=None):
         Example::
             tags = client.get_object_tags("my-bucket", "my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         query_params = {"versionId": version_id} if version_id else {}
         query_params["tagging"] = ""
@@ -2459,7 +2452,7 @@ def set_object_tags(self, bucket_name, object_name, tags, version_id=None):
             tags["User"] = "jsmith"
             client.set_object_tags("my-bucket", "my-object", tags)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if not isinstance(tags, Tags):
             raise ValueError("tags must be Tags type")
@@ -2488,7 +2481,7 @@ def enable_object_legal_hold(
         Example::
             client.enable_object_legal_hold("my-bucket", "my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         body = marshal(LegalHold(True))
         query_params = {"versionId": version_id} if version_id else {}
@@ -2515,7 +2508,7 @@ def disable_object_legal_hold(
         Example::
             client.disable_object_legal_hold("my-bucket", "my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         body = marshal(LegalHold(False))
         query_params = {"versionId": version_id} if version_id else {}
@@ -2545,7 +2538,7 @@ def is_object_legal_hold_enabled(
             else:
                 print("legal hold is not enabled on my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         query_params = {"versionId": version_id} if version_id else {}
         query_params["legal-hold"] = ""
@@ -2586,7 +2579,7 @@ def get_object_lock_config(self, bucket_name):
         Example::
             config = client.get_object_lock_config("my-bucket")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         response = self._execute(
             "GET", bucket_name, query_params={"object-lock": ""},
         )
@@ -2603,7 +2596,7 @@ def set_object_lock_config(self, bucket_name, config):
             config = ObjectLockConfig(GOVERNANCE, 15, DAYS)
             client.set_object_lock_config("my-bucket", config)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         if not isinstance(config, ObjectLockConfig):
             raise ValueError("config must be ObjectLockConfig type")
         body = marshal(config)
@@ -2629,7 +2622,7 @@ def get_object_retention(
         Example::
             config = client.get_object_retention("my-bucket", "my-object")
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         query_params = {"versionId": version_id} if version_id else {}
         query_params["retention"] = ""
@@ -2663,7 +2656,7 @@ def set_object_retention(
             )
             client.set_object_retention("my-bucket", "my-object", config)
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
         check_non_empty_string(object_name)
         if not isinstance(config, Retention):
             raise ValueError("config must be Retention type")
@@ -2718,7 +2711,7 @@ def upload_snowball_objects(self, bucket_name, object_list, metadata=None,
                 ],
             )
         """
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
 
         object_name = f"snowball.{random()}.tar"
 
@@ -2780,7 +2773,7 @@ def _list_objects(  # pylint: disable=too-many-arguments,too-many-branches
         policies.
         """
 
-        check_bucket_name(bucket_name)
+        check_bucket_name(bucket_name, s3_check=self._base_url.is_aws_host)
 
         if version_id_marker:
             include_version = True
diff --git a/minio/helpers.py b/minio/helpers.py
index b955d8790..712050a2c 100644
--- a/minio/helpers.py
+++ b/minio/helpers.py
@@ -37,18 +37,36 @@
 MAX_PART_SIZE = 5 * 1024 * 1024 * 1024  # 5GiB
 MIN_PART_SIZE = 5 * 1024 * 1024  # 5MiB
 
-_VALID_BUCKETNAME_REGEX = re.compile(
-    '^[A-Za-z0-9][A-Za-z0-9\\.\\-\\_\\:]{1,61}[A-Za-z0-9]$')
-_VALID_BUCKETNAME_STRICT_REGEX = re.compile(
-    '^[a-z0-9][a-z0-9\\.\\-]{1,61}[a-z0-9]$')
-_VALID_IP_ADDRESS = re.compile(
-    r'^(\d+\.){3}\d+$')
-_ALLOWED_HOSTNAME_REGEX = re.compile(
-    '^((?!-)(?!_)[A-Z_\\d-]{1,63}(?<!-)(?<!_)\\.)*((?!_)(?!-)' +
-    '[A-Z_\\d-]{1,63}(?<!-)(?<!_))$',
+_AWS_S3_PREFIX = (r'^(((bucket\.|accesspoint\.)'
+                  r'vpce(-(?!_)[a-z_\d]+(?<!-)(?<!_))+\.s3\.)|'
+                  r'((?!s3)(?!-)(?!_)[a-z_\d-]{1,63}(?<!-)(?<!_)\.)'
+                  r's3-control(-(?!_)[a-z_\d]+(?<!-)(?<!_))*\.|'
+                  r'(s3(-(?!_)[a-z_\d]+(?<!-)(?<!_))*\.))')
+
+_BUCKET_NAME_REGEX = re.compile(r'^[a-z0-9][a-z0-9\.\-]{1,61}[a-z0-9]$')
+_OLD_BUCKET_NAME_REGEX = re.compile(r'^[a-z0-9][a-z0-9_\.\-\:]{1,61}[a-z0-9]$',
+                                    re.IGNORECASE)
+_IPV4_REGEX = re.compile(
+    r'^((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\.){3}'
+    r'(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])$')
+_HOSTNAME_REGEX = re.compile(
+    r'^((?!-)(?!_)[a-z_\d-]{1,63}(?<!-)(?<!_)\.)*'
+    r'((?!_)(?!-)[a-z_\d-]{1,63}(?<!-)(?<!_))$',
     re.IGNORECASE)
-
-_EXTRACT_REGION_REGEX = re.compile('s3[.-]?(.+?).amazonaws.com')
+_AWS_ENDPOINT_REGEX = re.compile(r'.*\.amazonaws\.com(|\.cn)$', re.IGNORECASE)
+_AWS_S3_ENDPOINT_REGEX = re.compile(
+    _AWS_S3_PREFIX +
+    r'((?!s3)(?!-)(?!_)[a-z_\d-]{1,63}(?<!-)(?<!_)\.)*'
+    r'amazonaws\.com(|\.cn)$',
+    re.IGNORECASE)
+_AWS_ELB_ENDPOINT_REGEX = re.compile(
+    r'^(?!-)(?!_)[a-z_\d-]{1,63}(?<!-)(?<!_)\.'
+    r'(?!-)(?!_)[a-z_\d-]{1,63}(?<!-)(?<!_)\.'
+    r'elb\.amazonaws\.com$',
+    re.IGNORECASE)
+_AWS_S3_PREFIX_REGEX = re.compile(_AWS_S3_PREFIX, re.IGNORECASE)
+_REGION_REGEX = re.compile(r'^((?!_)(?!-)[a-z_\d-]{1,63}(?<!-)(?<!_))$',
+                           re.IGNORECASE)
 
 
 def quote(resource, safe='/', encoding=None, errors=None):
@@ -174,43 +192,34 @@ def makedirs(path):
             raise ValueError(f"path {path} is not a directory") from exc
 
 
-def check_bucket_name(bucket_name, strict=False):
+def check_bucket_name(bucket_name, strict=False, s3_check=False):
     """Check whether bucket name is valid optional with strict check or not."""
 
-    # Verify bucket name is not empty
-    bucket_name = str(bucket_name).strip()
-    if not bucket_name:
-        raise ValueError('Bucket name cannot be empty.')
-
-    # Verify bucket name length.
-    if len(bucket_name) < 3:
-        raise ValueError('Bucket name cannot be less than'
-                         ' 3 characters.')
-    if len(bucket_name) > 63:
-        raise ValueError('Bucket name cannot be greater than'
-                         ' 63 characters.')
+    if strict:
+        if not _BUCKET_NAME_REGEX.match(bucket_name):
+            raise ValueError('invalid bucket name {bucket_name}')
+    else:
+        if not _OLD_BUCKET_NAME_REGEX.match(bucket_name):
+            raise ValueError('invalid bucket name {bucket_name}')
 
-    match = _VALID_IP_ADDRESS.match(bucket_name)
-    if match:
-        raise ValueError('Bucket name cannot be an ip address')
+    if _IPV4_REGEX.match(bucket_name):
+        raise ValueError('bucket name {bucket_name} must not be formatted '
+                         'as an IP address')
 
     unallowed_successive_chars = ['..', '.-', '-.']
     if any(x in bucket_name for x in unallowed_successive_chars):
-        raise ValueError('Bucket name contains invalid '
-                         'successive chars '
-                         + str(unallowed_successive_chars) + '.')
-
-    if strict:
-        match = _VALID_BUCKETNAME_STRICT_REGEX.match(bucket_name)
-        if (not match) or match.end() != len(bucket_name):
-            raise ValueError('Bucket name contains invalid '
-                             'characters (strictly enforced).')
-
-    match = _VALID_BUCKETNAME_REGEX.match(bucket_name)
-    if (not match) or match.end() != len(bucket_name):
-        raise ValueError(
-            f"Bucket name does not follow S3 standards. Bucket: {bucket_name}",
-        )
+        raise ValueError('bucket name {bucket_name} contains invalid '
+                         'successive characters')
+
+    if (
+            s3_check and
+            bucket_name.startswith("xn--") or
+            bucket_name.endswith("-s3alias") or
+            bucket_name.endswith("--ol-s3")
+    ):
+        raise ValueError("bucket name {bucket_name} must not start with "
+                         "'xn--' and must not end with '--s3alias' or "
+                         "'--ol-s3'")
 
 
 def check_non_empty_string(string):
@@ -365,22 +374,57 @@ def genheaders(headers, sse, tags, retention, legal_hold):
     return headers
 
 
-def _extract_region(host):
-    """Extract region from Amazon S3 host."""
+def _get_aws_info(host, https, region):
+    """Extract AWS domain information. """
 
-    tokens = host.split(".")
-    token = tokens[1]
+    if not _HOSTNAME_REGEX.match(host):
+        return (None, None)
 
-    # If token is "dualstack", then region might be in next token.
-    if token == "dualstack":
-        token = tokens[2]
+    if _AWS_ELB_ENDPOINT_REGEX.match(host):
+        region_in_host = host.split(".elb.amazonaws.com", 1)[0].split(".")[-1]
+        return (None, region or region_in_host)
 
-    # If token is equal to "amazonaws", region is not passed in the host.
-    if token == "amazonaws":
-        return None
+    if not _AWS_ENDPOINT_REGEX.match(host):
+        return (None, None)
+
+    if not _AWS_S3_ENDPOINT_REGEX.match(host):
+        raise ValueError(f"invalid Amazon AWS host {host}")
 
-    # Return token as region.
-    return token
+    end = _AWS_S3_PREFIX_REGEX.match(host).end()
+    aws_s3_prefix = host[:end]
+
+    if "s3-accesspoint" in aws_s3_prefix and not https:
+        raise ValueError(f"use HTTPS scheme for host {host}")
+
+    tokens = host[end:].split(".")
+    dualstack = tokens[0] == "dualstack"
+    if dualstack:
+        tokens = tokens[1:]
+    region_in_host = None
+    if tokens[0] not in ["vpce", "amazonaws"]:
+        region_in_host = tokens[0]
+        tokens = tokens[1:]
+    aws_domain_suffix = ".".join(tokens)
+
+    if host in "s3-external-1.amazonaws.com":
+        region_in_host = "us-east-1"
+
+    if host in ["s3-us-gov-west-1.amazonaws.com",
+                "s3-fips-us-gov-west-1.amazonaws.com"]:
+        region_in_host = "us-gov-west-1"
+
+    if (aws_domain_suffix.endswith(".cn") and
+        not aws_s3_prefix.endswith("s3-accelerate.") and
+        not region_in_host and
+            not region):
+        raise ValueError(
+            f"region missing in Amazon S3 China endpoint {host}",
+        )
+
+    return ({"s3_prefix": aws_s3_prefix,
+             "domain_suffix": aws_domain_suffix,
+             "region": region or region_in_host,
+             "dualstack": dualstack}, None)
 
 
 class BaseURL:
@@ -423,42 +467,22 @@ def __init__(self, endpoint, region):
         ):
             url = url_replace(url, netloc=host)
 
-        self._accelerate_host_flag = host.startswith("s3-accelerate.")
-        self._is_aws_host = (
-            (
-                host.startswith("s3.") or self._accelerate_host_flag
-            ) and
-            (
-                host.endswith(".amazonaws.com") or
-                host.endswith(".amazonaws.com.cn")
-            )
-        )
+        if region and not _REGION_REGEX.match(region):
+            raise ValueError(f"invalid region {region}")
+
+        self._aws_info, region_in_host = _get_aws_info(
+            host, url.scheme == "https", region)
         self._virtual_style_flag = (
-            self._is_aws_host or host.endswith("aliyuncs.com")
+            self._aws_info or host.endswith("aliyuncs.com")
         )
-
-        region_in_host = None
-        if self._is_aws_host:
-            is_aws_china_host = host.endswith(".cn")
-            url = url_replace(
-                url,
-                netloc=(
-                    "amazonaws.com.cn"
-                    if is_aws_china_host else "amazonaws.com"
-                ),
-            )
-            region_in_host = _extract_region(host)
-
-            if is_aws_china_host and not region_in_host and not region:
-                raise ValueError(
-                    f"region missing in Amazon S3 China endpoint {endpoint}",
-                )
-            self._dualstack_host_flag = ".dualstack." in host
-        else:
-            self._accelerate_host_flag = False
-
         self._url = url
         self._region = region or region_in_host
+        self._accelerate_host_flag = False
+        if self._aws_info:
+            self._region = self._aws_info["region"]
+            self._accelerate_host_flag = (
+                self._aws_info["s3_prefix"].endswith("s3-accelerate.")
+            )
 
     @property
     def region(self):
@@ -478,29 +502,41 @@ def host(self):
     @property
     def is_aws_host(self):
         """Check if URL points to AWS host."""
-        return self._is_aws_host
+        return self._aws_info is not None
+
+    @property
+    def aws_s3_prefix(self):
+        """Get AWS S3 domain prefix."""
+        return self._aws_info["s3_prefix"] if self._aws_info else None
+
+    @aws_s3_prefix.setter
+    def aws_s3_prefix(self, s3_prefix):
+        """Set AWS s3 domain prefix."""
+        if not _AWS_S3_PREFIX_REGEX.match(s3_prefix):
+            raise ValueError(f"invalid AWS S3 domain prefix {s3_prefix}")
+        if self._aws_info:
+            self._aws_info["s3_prefix"] = s3_prefix
 
     @property
     def accelerate_host_flag(self):
-        """Check if URL points to AWS accelerate host."""
+        """Get AWS accelerate host flag."""
         return self._accelerate_host_flag
 
     @accelerate_host_flag.setter
     def accelerate_host_flag(self, flag):
-        """Check if URL points to AWS accelerate host."""
-        if self._is_aws_host:
-            self._accelerate_host_flag = flag
+        """Set AWS accelerate host flag."""
+        self._accelerate_host_flag = flag
 
     @property
     def dualstack_host_flag(self):
         """Check if URL points to AWS dualstack host."""
-        return self._dualstack_host_flag
+        return self._aws_info["dualstack"] if self._aws_info else False
 
     @dualstack_host_flag.setter
     def dualstack_host_flag(self, flag):
-        """Check to use virtual style or not."""
-        if self._is_aws_host:
-            self._dualstack_host_flag = flag
+        """Set AWS dualstack host."""
+        if self._aws_info:
+            self._aws_info["dualstack"] = flag
 
     @property
     def virtual_style_flag(self):
@@ -512,17 +548,67 @@ def virtual_style_flag(self, flag):
         """Check to use virtual style or not."""
         self._virtual_style_flag = flag
 
+    def _build_aws_url(self, url, bucket_name, enforce_path_style, region):
+        """Build URL for given information."""
+        s3_prefix = self._aws_info["s3_prefix"]
+        domain_suffix = self._aws_info["domain_suffix"]
+
+        host = f"{s3_prefix}{domain_suffix}"
+        if host in ["s3-external-1.amazonaws.com",
+                    "s3-us-gov-west-1.amazonaws.com",
+                    "s3-fips-us-gov-west-1.amazonaws.com"]:
+            return url_replace(url, netloc=host)
+
+        netloc = s3_prefix
+        if "s3-accelerate" in s3_prefix:
+            if "." in bucket_name:
+                raise ValueError(
+                    f"bucket name '{bucket_name}' with '.' is not allowed "
+                    f"for accelerate endpoint"
+                )
+            if enforce_path_style:
+                netloc = netloc.replace("-accelerate", "", 1)
+
+        if self._aws_info["dualstack"]:
+            netloc += "dualstack."
+        if "s3-accelerate" not in s3_prefix:
+            netloc += region + "."
+        netloc += domain_suffix
+
+        return url_replace(url, netloc=netloc)
+
+    def _build_list_buckets_url(self, url, region):
+        """Build URL for ListBuckets API."""
+        if not self._aws_info:
+            return url
+
+        s3_prefix = self._aws_info["s3_prefix"]
+        domain_suffix = self._aws_info["domain_suffix"]
+
+        host = f"{s3_prefix}{domain_suffix}"
+        if host in ["s3-external-1.amazonaws.com",
+                    "s3-us-gov-west-1.amazonaws.com",
+                    "s3-fips-us-gov-west-1.amazonaws.com"]:
+            return url_replace(url, netloc=host)
+
+        if s3_prefix.startswith("s3.") or s3_prefix.startswith("s3-"):
+            s3_prefix = "s3."
+            cn_suffix = ".cn" if domain_suffix.endswith(".cn") else ""
+            domain_suffix = f"amazonaws.com{cn_suffix}"
+        return url_replace(url, netloc=f"{s3_prefix}{region}.{domain_suffix}")
+
     def build(
             self, method, region,
             bucket_name=None, object_name=None, query_params=None,
     ):
         """Build URL for given information."""
-
         if not bucket_name and object_name:
             raise ValueError(
                 f"empty bucket name for object name {object_name}",
             )
 
+        url = url_replace(self._url, path="/")
+
         query = []
         for key, values in sorted((query_params or {}).items()):
             values = values if isinstance(values, (list, tuple)) else [values]
@@ -530,15 +616,10 @@ def build(
                 f"{queryencode(key)}={queryencode(value)}"
                 for value in sorted(values)
             ]
-        url = url_replace(self._url, query="&".join(query))
-        host = self._url.netloc
+        url = url_replace(url, query="&".join(query))
 
         if not bucket_name:
-            url = url_replace(url, path="/")
-            return (
-                url_replace(url, netloc="s3." + region + "." + host)
-                if self._is_aws_host else url
-            )
+            return self._build_list_buckets_url(url, region)
 
         enforce_path_style = (
             # CreateBucket API requires path style in Amazon AWS S3.
@@ -552,40 +633,21 @@ def build(
             ("." in bucket_name and self._url.scheme == "https")
         )
 
-        if self._is_aws_host:
-            s3_domain = "s3."
-            if self._accelerate_host_flag:
-                if "." in bucket_name:
-                    raise ValueError(
-                        f"bucket name '{bucket_name}' with '.' is not allowed "
-                        f"for accelerated endpoint"
-                    )
-
-                if not enforce_path_style:
-                    s3_domain = "s3-accelerate."
+        if self._aws_info:
+            url = self._build_aws_url(
+                url, bucket_name, enforce_path_style, region)
 
-            dual_stack = "dualstack." if self._dualstack_host_flag else ""
-            endpoint = s3_domain + dual_stack
-            if enforce_path_style or not self._accelerate_host_flag:
-                endpoint += region + "."
-            host = endpoint + host
+        netloc = url.netloc
+        path = "/"
 
         if enforce_path_style or not self._virtual_style_flag:
-            url = url_replace(url, netloc=host)
-            url = url_replace(url, path="/" + bucket_name)
+            path = f"/{bucket_name}"
         else:
-            url = url_replace(
-                url,
-                netloc=bucket_name + "." + host,
-                path="/",
-            )
-
+            netloc = f"{bucket_name}.{netloc}"
         if object_name:
-            path = url.path
             path += ("" if path.endswith("/") else "/") + quote(object_name)
-            url = url_replace(url, path=path)
 
-        return url
+        return url_replace(url, netloc=netloc, path=path)
 
 
 class ObjectWriteResult:
diff --git a/tests/unit/helpers.py b/tests/unit/helpers.py
index c37fc5c53..5fc54333c 100644
--- a/tests/unit/helpers.py
+++ b/tests/unit/helpers.py
@@ -14,6 +14,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from collections import namedtuple
+from unittest import TestCase
+from urllib.parse import urlunsplit
+
+from minio.helpers import BaseURL
+
 
 def generate_error(code, message, request_id, host_id,
                    resource, bucket_name, object_name):
@@ -29,3 +35,1741 @@ def generate_error(code, message, request_id, host_id,
     </Error>
     '''.format(code, message, request_id, host_id,
                resource, bucket_name, object_name)
+
+
+class BaseURLTests(TestCase):
+    def test_aws_new_baseurl_error(self):
+        cases = [
+            # invalid Amazon AWS host error
+            "https://z3.amazonaws.com",
+            "https://1234567890.s3.amazonaws.com",
+            "https://1234567890.s3-accelerate.amazonaws.com",
+            "https://1234567890.abcdefgh.s3-control.amazonaws.com",
+            "https://s3fips.amazonaws.com",
+            "https://s3-fips.s3.amazonaws.com",
+            "https://s3-fips.s3accelerate.amazonaws.com",
+            "https://s3-fips.s3-accelerate.amazonaws.com",
+            "https://bucket.vpce.s3.us-east-1.vpce.amazonaws.com",
+            "https://bucket.bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+            "vpce.amazonaws.com",
+            "https://accesspoint.accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+            "vpce.amazonaws.com",
+            "https://accesspoint.vpce-1123.vpce-xyz.s3.amazonaws.com",
+            # use HTTPS scheme for host error
+            "http://s3-accesspoint.amazonaws.com",
+            # region missing in Amazon S3 China endpoint error
+            "https://s3.amazonaws.com.cn",
+        ]
+        for endpoint in cases:
+            self.assertRaises(ValueError, BaseURL, endpoint, None)
+
+    def test_aws_new_baseurl(self):
+        Case = namedtuple("Case", ["args", "result"])
+        cases = [
+            Case(
+                ("https://s3.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3.amazonaws.com", "ap-south-1a"),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3.us-gov-east-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3.me-south-1.amazonaws.com", "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3.dualstack.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3.dualstack.amazonaws.com", "ap-south-1a"),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3.dualstack.us-gov-east-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.amazonaws.com", "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.us-gov-east-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.us-gov-east-1.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accelerate.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-fips.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-fips.amazonaws.com", "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-fips.us-gov-east-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-fips.me-south-1.amazonaws.com", "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-fips.dualstack.us-gov-east-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-fips.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-external-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-external-1.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-us-gov-west-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-us-gov-west-1.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-west-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-fips-us-gov-west-1.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-fips-us-gov-west-1.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-west-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                {
+                    "s3_prefix": "bucket.vpce-1a2b3c4d-5e6f.s3.",
+                    "domain_suffix": "vpce.amazonaws.com",
+                    "region": "us-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                {
+                    "s3_prefix": "accesspoint.vpce-1a2b3c4d-5e6f.s3.",
+                    "domain_suffix": "vpce.amazonaws.com",
+                    "region": "us-east-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com", None),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "012345678901.s3-control.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com", None),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "012345678901.s3-control-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accesspoint.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com", None),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": False,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": False,
+                },
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": None,
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "ap-south-1a",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "us-gov-east-1",
+                    "dualstack": True,
+                },
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                {
+                    "s3_prefix": "s3-accesspoint-fips.",
+                    "domain_suffix": "amazonaws.com",
+                    "region": "cn-northwest-1",
+                    "dualstack": True,
+                },
+            ),
+            ###
+            Case(
+                ("https://my-load-balancer-1234567890.us-west-2.elb."
+                 "amazonaws.com", "us-west-2"),
+                None,
+            ),
+        ]
+
+        for case in cases:
+            url = BaseURL(*case.args)
+            self.assertEqual(url._aws_info, case.result)
+
+    def test_aws_list_buckets_build(self):
+        Case = namedtuple("Case", ["args", "result"])
+        cases = [
+            Case(
+                ("https://s3.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.amazonaws.com", "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.us-gov-east-1.amazonaws.com", None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3.dualstack.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.amazonaws.com", "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.us-gov-east-1.amazonaws.com", None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.amazonaws.com", "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.us-gov-east-1.amazonaws.com", None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-external-1.amazonaws.com", None),
+                "https://s3-external-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-us-gov-west-1.amazonaws.com", None),
+                "https://s3-us-gov-west-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips-us-gov-west-1.amazonaws.com", None),
+                "https://s3-fips-us-gov-west-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/",
+            ),
+            Case(
+                ("https://accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com", None),
+                "https://012345678901.s3-control.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com",
+                 "ap-south-1a"),
+                "https://012345678901.s3-control.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://012345678901.s3-control.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://012345678901.s3-control.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 None),
+                "https://012345678901.s3-control.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://012345678901.s3-control.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://012345678901.s3-control.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://012345678901.s3-control.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com", None),
+                "https://012345678901.s3-control-fips.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://012345678901.s3-control-fips.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://012345678901.s3-control-fips.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://012345678901.s3-control-fips.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 None),
+                "https://012345678901.s3-control-fips.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://012345678901.s3-control-fips.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://012345678901.s3-control-fips.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://012345678901.s3-control-fips.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.amazonaws.com",
+                 "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com", None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 None),
+                "https://s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://my-load-balancer-1234567890.us-west-2.elb."
+                 "amazonaws.com", "us-west-2"),
+                "https://my-load-balancer-1234567890.us-west-2.elb."
+                "amazonaws.com/",
+            ),
+        ]
+
+        for case in cases:
+            base_url = BaseURL(*case.args)
+            url = urlunsplit(base_url.build(
+                "GET", base_url.region or "us-east-1"))
+            self.assertEqual(str(url), case.result)
+
+    def test_aws_bucket_build(self):
+        Case = namedtuple("Case", ["args", "result"])
+        cases = [
+            Case(
+                ("https://s3.amazonaws.com", None),
+                "https://my-bucket.s3.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://my-bucket.s3.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3.dualstack.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3.dualstack.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3.dualstack.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3.dualstack.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-accelerate.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accelerate.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.amazonaws.com", None),
+                "https://my-bucket.s3-fips.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-fips.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://my-bucket.s3-fips.cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3-fips.dualstack.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-fips.dualstack.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips.dualstack.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-fips.dualstack.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-external-1.amazonaws.com", None),
+                "https://my-bucket.s3-external-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-us-gov-west-1.amazonaws.com", None),
+                "https://my-bucket.s3-us-gov-west-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-fips-us-gov-west-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips-us-gov-west-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://my-bucket.bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/",
+            ),
+            Case(
+                ("https://accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://my-bucket.accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com", None),
+                "https://my-bucket.012345678901.s3-control.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.dualstack.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com", None),
+                "https://my-bucket.012345678901.s3-control-fips.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control-fips.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control-fips.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.amazonaws.com", None),
+                "https://my-bucket.s3-accesspoint.us-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint.ap-south-1a.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.us-gov-east-1.amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.dualstack.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint.dualstack.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.dualstack.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint.dualstack.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com", None),
+                "https://my-bucket.s3-accesspoint-fips.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint-fips.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint-fips.cn-northwest-1."
+                "amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.us-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.ap-south-1a."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.us-gov-east-1."
+                "amazonaws.com/",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint-fips.dualstack."
+                "cn-northwest-1.amazonaws.com/",
+            ),
+            ###
+            Case(
+                ("https://my-load-balancer-1234567890.us-west-2.elb."
+                 "amazonaws.com", "us-west-2"),
+                "https://my-load-balancer-1234567890.us-west-2.elb."
+                "amazonaws.com/my-bucket",
+            ),
+        ]
+
+        for case in cases:
+            base_url = BaseURL(*case.args)
+            url = urlunsplit(base_url.build(
+                "GET", base_url.region or "us-east-1", bucket_name="my-bucket"))
+            self.assertEqual(str(url), case.result)
+
+    def test_aws_object_build(self):
+        Case = namedtuple("Case", ["args", "result"])
+        cases = [
+            Case(
+                ("https://s3.amazonaws.com", None),
+                "https://my-bucket.s3.us-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3.ap-south-1a.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3.us-gov-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://my-bucket.s3.cn-northwest-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3.dualstack.us-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3.dualstack.ap-south-1a.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3.dualstack.us-gov-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3.dualstack.cn-northwest-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-accelerate.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accelerate.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accelerate.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accelerate.dualstack.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.amazonaws.com", None),
+                "https://my-bucket.s3-fips.us-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-fips.ap-south-1a.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips.us-gov-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.me-south-1.amazonaws.com", "cn-northwest-1"),
+                "https://my-bucket.s3-fips.cn-northwest-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", None),
+                "https://my-bucket.s3-fips.dualstack.us-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.amazonaws.com", "ap-south-1a"),
+                "https://my-bucket.s3-fips.dualstack.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.us-gov-east-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips.dualstack.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips.dualstack.me-south-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-fips.dualstack.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-external-1.amazonaws.com", None),
+                "https://my-bucket.s3-external-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-us-gov-west-1.amazonaws.com", None),
+                "https://my-bucket.s3-us-gov-west-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-fips-us-gov-west-1.amazonaws.com", None),
+                "https://my-bucket.s3-fips-us-gov-west-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://my-bucket.bucket.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                 "vpce.amazonaws.com", None),
+                "https://my-bucket.accesspoint.vpce-1a2b3c4d-5e6f.s3.us-east-1."
+                "vpce.amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com", None),
+                "https://my-bucket.012345678901.s3-control.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.dualstack.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "ap-south-1a.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "us-gov-east-1.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control.dualstack."
+                "cn-northwest-1.amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com", None),
+                "https://my-bucket.012345678901.s3-control-fips.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control-fips.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control-fips.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "us-east-1.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "ap-south-1a.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "us-gov-east-1.amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://012345678901.s3-control-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.012345678901.s3-control-fips.dualstack."
+                "cn-northwest-1.amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.amazonaws.com", None),
+                "https://my-bucket.s3-accesspoint.us-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint.ap-south-1a.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.us-gov-east-1.amazonaws.com/"
+                "path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.us-gov-east-1.amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.dualstack.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint.dualstack.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint.dualstack.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint.dualstack.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com", None),
+                "https://my-bucket.s3-accesspoint-fips.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint-fips.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint-fips.cn-northwest-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.us-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.amazonaws.com",
+                 "ap-south-1a"),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.ap-south-1a."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 None),
+                "https://my-bucket.s3-accesspoint-fips.dualstack.us-gov-east-1."
+                "amazonaws.com/path/to/my/object",
+            ),
+            Case(
+                ("https://s3-accesspoint-fips.dualstack.us-gov-east-1."
+                 "amazonaws.com",
+                 "cn-northwest-1"),
+                "https://my-bucket.s3-accesspoint-fips.dualstack."
+                "cn-northwest-1.amazonaws.com/path/to/my/object",
+            ),
+            ###
+            Case(
+                ("https://my-load-balancer-1234567890.us-west-2.elb."
+                 "amazonaws.com", "us-west-2"),
+                "https://my-load-balancer-1234567890.us-west-2.elb."
+                "amazonaws.com/my-bucket/path/to/my/object",
+            ),
+        ]
+
+        for case in cases:
+            base_url = BaseURL(*case.args)
+            url = urlunsplit(base_url.build(
+                "GET", base_url.region or "us-east-1",
+                bucket_name="my-bucket", object_name="path/to/my/object"))
+            self.assertEqual(str(url), case.result)