This site represents one of the bigger challenges we've faced. It was not really technically challenging. The real challenge lie in figuring out how to best implement the client's request to have 5 full websites under the banner of one master site. Separate, but not apart.
If that doesn't even begin to make sense, then you're beginning to understand why it was hard to implement! Here's a better explanation:
The typical method for "merging" multiple sites together would either entail gathering the content from multiple sites and then finding a nice way of organizing it under the banner of a single site. But that's not really what the client wanted. The other way would be to create "subdomains" and actually run separate sites under the same location. Not what the client wanted, either!
The end result of our organization challenge was to put all the content under one "roof", organized by master sections (the old website names). As each article or image is pulled from the database, the site examines what section it belongs to and then changes the site template, logo, and menu items to match the content.
Separate. But together!