The Castle Project web site is powered by Jekyll and GitHub Pages.
How to build the site locally:
# make sure you've got ruby, 1.9.3 or 2.0.0 will do
ruby --version
# install bundler, if you don't already have it
gem install bundler
# install the github-pages package using our Gemfile
bundle install
# start the web server which will keep regenerating the files in _site when you make changes
bundle exec jekyll serve --watch
If you run into any problems, check the GitHub Pages Jekyll documentation first.