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).
Taipei 101
Various sources, including the building's owners, give the height of Taipei 101 as , roof height and top floor height as and . This lower figure is derived by measuring from the top of a platform at the base. CTBUH standards, though, include the height of the platform in calculating the overall height, as it represents part of the man-made structure and is above the level of the surrounding pavement. Taipei 101 displaced the Petronas Towers as the tallest building in the world by . The record it claimed for greatest height from ground to pinnacle was surpassed by the Burj Khalifa in Dubai, which is in height. Taipei 101's records for roof height and highest occupied floor briefly passed to the Shanghai World Financial Center in 2008, which in turn yielded these records as well to the Burj.