What is the highest building in the world?
The world's tallest human-made structure is the **Burj Khalifa** in Dubai, United Arab Emirates, at ***828 meters tall (2,717 ft)***. The building gained the official title of tallest building in the world and the tallest self-supported structure at its opening on January 9, 2010. The Burj Khalifa exceeds the height of the Tokyo Skytree (634m, 2,080ft), which is the second-tallest self-supporting structure as well as the tallest tower in the world (but not the tallest building).  

By April 8, 2008 the Burj Khalifa had been built higher than the KVLY-TV mast in North Dakota, US. That September it officially surpassed Poland's 646.38 m (2,120.7 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 Petronius Platform stands 610 m (2,000 ft) off the sea floor, leading some, including Guinness World Records 2007, to claim it as the tallest freestanding structure in the world, until surpassed by the Burj Khalifa in 2010. However, it is debated whether underwater height should be counted, in the same manner as height below ground 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 m (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. Despite this, Guinness World Records 2009 listed the Ursa tension leg platform as the tallest structure in the world with a total height of 1,306 m (4,285 ft). The Magnolia Tension-leg Platform in the Gulf of Mexico is even taller with a total height of 1,432 m (4,698 ft).

Taipei 101 in Taipei, Taiwan, set records in three of the four skyscraper categories at the time it opened in 2004; at the time the Burj Khalifa opened in 2010 it remained the world's tallest inhabited building 509.2 m (1,671 ft) as measured to its architectural height (spire). The height of its roof 449.2 m (1,474 ft) and highest occupied floor 439.2 m (1,441 ft) had been surpassed by the Shanghai World Financial Center with corresponding heights of 487 and 474 m (1,598 and 1,555 ft). Willis Tower (formerly Sears Tower) was the highest in the final category: the greatest height to top of antenna of any building in the world at 527 m (1,729 ft).

Burj Khalifa broke the height record in all four categories for completed buildings.

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