Philadelphia skyline

Philadelphia, the largest city in the U.S. state of Pennsylvania, is home to 389 completed high-rises, 32 of which stand taller than 400 feet (122 m). The tallest building in the city is currently the 58-story Comcast Center, which rises 975 feet (297 m) in Center City. Comcast Center is also the tallest building in Pennsylvania and the 20th-tallest building in the United States. The second-tallest building is One Liberty Place, which rises 61 floors and 945 feet (288 m). One Liberty Place stood as the tallest building in Pennsylvania for over 20 years until the completion of Comcast Center in 2008. Overall, seven of the ten tallest buildings in Pennsylvania are in Philadelphia, with the remainder being in Pittsburgh. Philadelphia is one of only five American cities with two or more completed buildings over 900 feet (270 m) tall.

Philadelphia's history of tall buildings is generally thought to have begun with the 1754 addition of the steeple to Christ Church, which was one of America's first high-rise structures. Through most of the 20th century, a "gentlemen's agreement" prevented buildings from rising higher than the 548-ft (167-m) Philadelphia City Hall. Despite this, Philadelphia amassed a large collection of high-rise buildings. The completion of One Liberty Place in 1987 broke the agreement, and Philadelphia has since seen the construction of eight skyscrapers that eclipse City Hall in height.

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 1.6 feet (0.49 m) 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.

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