Which are the tallest buildings in the world?

The subject of the tallest building in the world should be simple, just measure the thing up to the top. This concept was working well until many different types of structures and buildings began being built.

Defining the tallest building

Overview
Following controversy in 1998 over whether the Sears Tower or the Petronas Twin Towers and its spires where taller, the Council on Tall Buildings and Urban Habitat (CTBUH) defined how the world's tallest buildings are measured.
The conclusion was that height is measured from the level of the lowest pedestrian entrance to architectural top including spires and pinnacles, but not antennas, masts or flagpoles and are habitable buildings with floors and walls throughout.

Burj Khalifa and Taipei 101

Tall buildings: The basics
The tallest building is the Burj Khalifa (formerly Burj Dubai) in The United Arab Emirates.
It was finished in 2010 and contains 163 habitable floors plus 46 maintenance levels in the spire and 2 parking levels in the basement and stands at a height of 828 meters (2,716 ft).
The second tallest building is the Taipei 101 in Taiwan. It stands at 504 meters (1667 ft) and contains 101 floors above ground and 5 floors underground.
It was formerly known as the Taipei World Financial Centre, and was ranked officially as the world's tallest from 2004 until the opening of the Burj Khalifa.

World Financial Centre and the Petronas Tower

Other tall buildings
The third tallest building is the World Financial Centre, Shanghai, China.
The building is 492 meters (1,614 ft) and consists of offices, hotels, conference rooms, observation decks, and shopping malls on the ground floors.
It is the tallest structure in the People's Republic of China and has the world's tallest observation deck with the highest view at 474 m (1,555 ft) above ground level. The first of the Petronas Towers in Kuala Lumpur, Malaysia is the fourth tallest building.
It stands at 452 meters (1,483 ft). The Petronas Towers (also known as the Petronas Twin Towers) were the tallest buildings in the world from 1998 to 2004 but remain the tallest twin buildings in the world.

The rest of the top ten

Final word
The fifth tallest building is the second of the Petronas Tower which is the identical height to the first tower at 452 meters.
The 450 meter (1476 ft) Greenland Financial Centre in Nanjing, China is the sixth highest and the Willis Tower (formerly Sears Tower) in Chicago the seventh at 442 meters (1,451 ft).
The eighth is the Guangzhou West Tower in Guangzhou, China 438 meters (1,435 ft), the ninth the Jin Mao Building, in Shanghai, China 421 meters (1,381 ft) and the 415 meter (1362 ft) Two International Finance Centre, Hong Kong complete the top ten.