Location: Las Vegas, Nev.
Developer: MGM Mirage, Taubman Centers
Master architect: Gensler
Size: 77 acres and will feature a 4,000-room casino, a pair of super-upscale nongaming hotels, 1,543 condominium units, residential towers with 810 lofts and 500,000 square feet of retail space.
Cost: $7.4 billion
Buzz: Expect an environmentally sustainable city-within-a-city on the Las Vegas Strip, designed by some of the world's most famous architects. It is the most expensive commercialin U.S. history.