List of tallest buildings and structures
The tallest artificial structure is Burj Khalifa, a skyscraper in Dubai that reached in height on January 17, 2009. By April 7, 2008 it had been built higher than the KVLY-TV mast in North Dakota, USA. That September it officially surpassed Poland's Warsaw radio mast, which stood from 1974 to 1991, to become the tallest structure ever built. Guyed lattice towers such as these masts had held the world height record since 1954.
List of tallest buildings in Philadelphia
Philadelphia has twice held the tallest habitable building in North America, first with Christ Church, then with City Hall. The latter reigned as the world's tallest building from 1894 to 1908, and is currently the world's second-tallest masonry building, only shorter than Mole Antonelliana in Turin. Like other large American cities, Philadelphia went through a massive building boom in the 1970s and 1980s, resulting in the completion of over 20 high-rise buildings.