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
Upon its completion, Taipei 101 was the world's tallest inhabited building, at as measured to its height architectural top (spire), exceeding the Petronas Towers, which were previously the tallest inhabited skyscraper at . The height to the top of the roof, at , and highest occupied floor, at , surpassed the previous records of and , respectively; the Willis Tower had previously held that distinction. It also surpassed the 85-story, Tuntex Sky Tower in Kaohsiung as the tallest building in Taiwan and the 51-story, Shin Kong Life Tower as the tallest building in Taipei. Taipei 101 claimed the official records for the world's tallest sundial and the world's largest New Year's Eve countdown clock.