There are secret cities at Walt Disney World the City of Bay Lake and the City of Lake Buena Vista. People actually live in them and they are chartered under Florida law. Not all governmental power could be given to the Reedy Creek Improvement District under the state constitution, so to safeguard control over the property, Disney created the two cities. The city councils control some end-use aspects of water, fire, police powers, some zoning issues, transportation and a few other non-RCID maters.
Of course, both cities are nothing more than trailer parks housing about thirty people all of whom are guaranteed to vote exactly according to Disneys wishes (imagine loosing not only your job but your house as well). All of the residents are renters since owning land would give them a seat on the Reedy Creek board and it's generally thought they all hold very low-end jobs at the resort.
If you look at the extreme northeast corner of Bay Lake you can see a small strip of beach that is part of the City of Bay Lake. If you get a boat close enough to it, you can usually see a few of the trailers.