Burj Khalifa

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A mixed-use tower in Dubai, 828 m tall to the tip of its spire with about 163 habitable floors, designed by Skidmore, Owings and Merrill and opened on 4 January 2010. Its structure is a buttressed core: a hexagonal reinforced-concrete core with three wings projecting from it, each wing terminating in a nose and each stepping back at a different level, so that the plan spirals as it rises. The wings buttress the core against wind in every direction and each setback changes the shape presented to the wind, which was the point - the setbacks were tuned in wind-tunnel testing to disrupt organised vortex shedding, the phenomenon that makes a uniform tall prism sway in resonance with its own wake. Reinforced concrete carries the tower to roughly level 156, above which a structural steel spire continues. As of the last state confirmable to this pack it remained the world's tallest building; Jeddah Tower in Saudi Arabia, resumed after a long halt, is the project intended to exceed it.