Location: Las Vegas, Nev.

Developer: MGM Mirage, Taubman Centers

Master architect: Gensler

Size: 77 acres and will feature a 4,000-room casino hotel, 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 commercial development in U.S. history.