CN Tower
"Guinness World Records" has called the CN Tower "the world's tallest self-supporting tower" and "the world's tallest free-standing tower". Although Guinness did list this description of the CN Tower under the heading "tallest building" at least once, it has also listed it under "tallest tower", omitting it from its list of "tallest buildings." In 1996, Guinness changed the tower's classification to "World's Tallest Building and Freestanding Structure". Emporis and the Council on Tall Buildings and Urban Habitat both listed the CN Tower as the world's tallest free-standing structure on land, and specifically state that the CN Tower is not a true building, thereby awarding the title of world's tallest building to Taipei 101, which is shorter than the CN Tower. The issue of what was tallest became moot when Burj Khalifa, then under construction, exceeded the height of the CN Tower in 2007 (see below).
List of tallest buildings
Until 1996, the world's tallest building was defined by the height to the top of the tallest architectural element, including spires but not antennae. This led to a rivalry between the Bank of Manhattan Building and the Chrysler Building. The Bank of Manhattan Building (aka 40 Wall Street) employed only a short spire and was 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 spire secretly assembled inside the building to claim the title of world's tallest building with a total height of , although it had a lower top occupied floor and a shorter height when both buildings' spires were excluded.