CHICAGO (AP) — The world's tallest skyscrapers tower above cities around the world. Eight of the 10 tallest are scattered throughout Asia in cities including Dubai, Taipei and Hong Kong. Two are in the United States — the Willis Tower in Chicago and 1 World Trade Center in New York.

On Tuesday, the monument to those killed in the Sept. 11, 2001, attacks became the tallest building in the United States, surpassing Chicago's skyscraper, after an international panel of architects with the Council on Tall Buildings and Urban Habitat announced that the needle atop the building can be counted when measuring the structure's height.

The ruling also will make 1 World Trade Center the third tallest building in the world when it is completed.

Ranking these tall buildings — and the rest of the world's tallest structures — is more mind-bending than one might think. Lists can vary depending, for example, on whether you count the broadcast antennas on top or whether you're judging them by highest usable floor.

Here is a photo gallery of the 10 tallest buildings the world, according to the Chicago-based council's classification of "architectural height." This includes spires, but not antennas, signs, flagpoles or other functional-technical equipment.

Dubai's Burj Khalifa is the tallest building in the world at 2,717 feet (828 meters). With Tuesday's decision, the Willis Tower will be the 10th tallest after the new World Trade Center opens, according to the council.

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Online:

Council on Tall Buildings and Urban Habitat: http://www.ctbuh.org/