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).
Council on Tall Buildings and Urban Habitat
The CTBUH maintains an extensive database of the tallest buildings in the world, organized by various categories. Buildings under construction are also included, although not ranked until completion. The CTBUH also produces an annual list of the ten tallest buildings completed in that particular year. Topping the 2008 list was the Shanghai World Financial Center in Shanghai, the then tallest building in the world according to the criteria of highest occupied floor, and home to the world's highest observation deck. Second on the 2008 list was the Almas Tower in Dubai, third was the Minsheng Bank Building in Wuhan which stands at , whilst fourth was The Address Downtown Burj Dubai (). All in all, six of the ten tallest buildings completed in 2008 are located in Asia, three in the Middle East and one in North America.