List of tallest buildings and structures
The world's tallest artificial structure is the Burj Khalifa in Dubai (of the United Arab Emirates). The building gained the official title of "Tallest Building in the World" and the tallest self-supported structure at its opening on January 9, 2010. The second-tallest self-supporting structure and the tallest tower is the Tokyo Skytree. The tallest guyed structure is the KVLY-TV mast.
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.