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).
First Canadian Place
First Canadian Place was the 6th tallest building in the world to structural top (currently 103rd) and the tallest building overall outside of Chicago and New York when built in 1975. It was also the tallest building in the Commonwealth of Nations until the completion of the Petronas Towers in Kuala Lumpur, Malaysia, in 1998. The Bank of Montreal "M-bar" logo at the top of the building was the highest sign in the world from 1975 until overtaken by the sign atop CITIC Plaza in 1997. The roof is still the location of a number of antennas used for radio and television broadcasting. The structure contains 29 elevators, and is one of only a few buildings in the world that uses the double-decked variety, and is connected to the underground PATH system.