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).
Empire State Building
The Empire State Building is a 102-story Art Deco skyscraper in Midtown Manhattan, New York City. Designed by Shreve, Lamb & Harmon and completed in 1931, the building has a roof height of and stands a total of tall, including its antenna. Its name is derived from "Empire State", the nickname of New York, which is of unknown origin. the building is the 5th-tallest completed skyscraper in the United States and the 28th-tallest in the world. It is also the 6th-tallest freestanding structure in the Americas.