Tallest Structure in the World

The tallest man-made structure is Burj Dubai, a skyscraper under construction in Dubai that reached 818 m (2,684 ft) in height on 17 January 2009. By 7 April 2008 it had been built higher than the KVLY-TV mast in North Dakota, USA, which is still the tallest completed structure at 628.8 m (2,063 ft).[3] In September it officially surpassed Poland's 646.38 m (2,121 ft) Warsaw radio mast, which stood from 1974 to 1991, to become the tallest structure ever built. Guyed lattice towers such as these masts had held the world height record since 1954.

The CN Tower in Toronto, Ontario, Canada, standing at 553.3 m (1,815 ft), is the world's tallest completed freestanding structure on land. Opened in 1976, it was surpassed in height by the rising Burj Dubai on September 12, 2007.[4][5][6] It has the world's second highest public observation deck at 446.5 m (1,465 ft).

The Petronius Platform stands 610 m (2,001 ft) off the sea floor leading some, including Guinness World Records 2007, to claim it as the tallest freestanding structure in the world. However, it is debated whether underwater height should be discounted in the same manner as height below grade is ignored on buildings.

The Troll A platform is 472 m (1,549 ft), without any part of that height being supported by wires. The tension-leg type of oil platform has even greater below-water heights with several examples more than 1,000 metres (3,300 ft) deep. However, these platforms are not considered constant structures as the vast majority of their height is made up of the length of the tendons attaching the floating platforms to the sea floor.

Taipei 101 in Taipei, Taiwan is currently the world's tallest inhabited building in only one of the four main categories that are commonly measured: at 509.2 m (1,671 ft) as measured to its architectural height (spire). Its roof height 449.2 m (1,474 ft) and highest occupied floor 439.2 m (1,441 ft) have recently been overtaken by the Shanghai World Financial Center (roof height 487 m (1,598 ft); highest occupied floor 474 m (1,555 ft)). Willis Tower (formerly Sears Tower) is highest in the final category: the greatest height to top of antenna of any building in the world at 527.3 m (1,730 ft).

On its completion, projected for late 2009, Burj Dubai will break the height record in all four categories for completed buildings by a wide margin. The Shanghai World Financial Center has the world's highest roof, highest occupied floor, and the world's highest public observation deck at 474.2 m (1,556 ft). It will retain the latter record after the completion of Burj Dubai, as Burj Dubai's observation deck will be at 442 m (1,450 ft).