Walt Disney World
Learning from the experience of California's Disneyland which opened in 1955 - lack of control over surrounding land and business development around the original park - Walt Disney was determined that this wouldn't happen again. The Disney Corporation began to secretly buy 27,500 acres of farmland in central Florida for just $6 million. This new site would be 100 times bigger than Disneyland, CA.
WDW opened it's first park, Magic Kingdom on 1st October 1971, followed by the ambitious EPCOT on 1st October 1982. Hollywood Studios (formerly Disney-MGM) 1st May 1989 and Animal Kingdom 22 April 1998. The four main theme parks are very separate entities and you should really allow a full day per park if you want to see everything.
My favourite quote from Disney after a phone conversation with reservations for a Character Breaksfast is " Well, you a have a bibbidi bobbidi kinda day!"