New Century Global Centre
Opening as recently as June of 2013, the New Century Global Centre in Chengdu, China, is the new title-holder for the largest building in the world by floor area. To get an idea of just how massive this structure is, consider that it is large enough to hold 20 Sydney Opera Houses and has three times the square footage of the Pentagon.
Within its walls are numerous offices, conference rooms, a massive shopping mall, two 1,000-room hotels, an ice-skating rink, a 14-screen IMAX theater, and even an artificial seaside village, complete with a man-made beach and the world's largest artificial wave generator. An artificial sun ensures that it's always daylight in this replica of paradise.