Adrian Smith, FAIA—who led design on the Burj Khalifa while still at Skidmore, Owings & Merrill—is outdoing even himself with his scheme for the Kingdom Tower in Jeddah, Saudi Arabia, which is slated to take over as the world’s tallest building with an overall height of more than 1 kilometer (3,280 feet). To combat the wind forces that occur with any building of this size—“the key to resisting wind forces in a tall building is shedding vortices,” Smith says—the highly reflective glass façade is continuously sloped, changing the dynamics at every floor and shrinking each successive floor plate 4 to 8 inches. The tower is supported by a central core, which is braced by 2-foot-thick concrete walls that line the double-loaded corridors in each of the three wings in the tripodal structure. The projected 5.7 million square feet of floor space will be occupied by a stacked program of office, hotel, and residential units, all serviced by a fleet of 59 elevators. A sky terrace, 100 feet in diameter, is cantilevered off of the 157th floor, roughly 2,000 feet in the air. First designed as a helipad—until “we started talking to helicopter pilots and they said ‘it gets dicey up there,’ ” Smith says—it will likely be used as a private terrace for a penthouse unit. Construction is expected to begin on the foundations soon, and the tower should be complete within the next five to six years.