What is the worlds tallest building?
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).
Shanghai Tower
The Shanghai Tower () is a , 128-story megatall skyscraper in Lujiazui, Pudong, Shanghai. It shares the record (along with the Ping An Finance Center) of having the world's highest observation deck within a building or structure at 562 m, and the 2nd world's fastest elevators at a top speed of . It is the world's second-tallest building by height to architectural top. However, the title of the world's fastest elevator now belongs to the Guangzhou CTF Finance Centre, with a top speed of achieved in 2017.