100 tallest completed buildings in the world. The council currently ranks Burj Khalifa as the tallest at 828 m (2,717 ft). The CTBUH only recognizes buildings that are complete, however, and some buildings listed within these list articles are not considered complete by the CTBUH.
In 1996, as a response to the dispute as to whether the Petronas Towers or the Willis Tower was taller, the council listed and ranked buildings in four categories:
- height of structural or architectural top
- height of highest floor
- height to the top of roof (removed as category November 2009)
- height to top of any part of the building.
Spires are considered integral parts of the architectural design of buildings, to which changes would substantially change the appearance and design of the building, whereas antennas may be added or removed without such consequences. This naturally hurts the rankings of buildings without spires, or with antennas instead of spires, or with shorter spires. The most famous such discrepancy is that Petronas Towers, with their spires, are ranked higher than the Willis Tower (formerly Sears Tower) with its antennas, despite the Petronas Towers' lower roofs and lower highest points (of spire/antenna).
However, this type of discrepancy has happened before, without resulting in a change of the criteria used to determine the world's tallest building, which until 1996 was the height to the top of the tallest architectural element (spires, but not antennae). A famous historical case of this discrepancy was the rivalry between 40 Wall Street building (then known as the Bank of Manhattan Building) and the Chrysler Building. The Bank of Manhattan Building employed only a short spire and was 927ft (283m) tall and had a much higher top occupied floor (the second category in the 1996 criteria for tallest building). In contrast, the Chrysler Building employed a very large 125ft (38m) spire secretly assembled inside the building to claim the title of world's tallest building with a total height of 1048 feet (319m), despite having a lower top occupied floor and a shorter height when both building's spires are not counted in their heights. Upset by Chrysler’s victory, Shreve & Lamb, the consulting architects of 40 Wall Street, wrote a newspaper article claiming that their building was actually the tallest, since it contained the world's highest usable floor. They pointed out that the observation deck in the Bank of Manhattan Building was nearly 100 feet (30m) above the top floor in the Chrysler Building, whose surpassing spire was strictly ornamental and essentially inaccessible. At present the issue of criteria is moot, as Burj Khalifa tops the list by some margin, regardless of which criterion is applied.