Where is the world’s largest municipal building?

Philadelphia’s City Hall stands at 548 feet (167 meters). While the Washington Monument is a masonry structure that stands at 555 feet, 5 inches, it is not habitable. City Hall’s granite and brick walls are as thick as 22 ft. (6.7 m) and the exterior includes granite, limestone, and marble. It was constructed over 30 years, between 1871 and 1901, at a cost of $24 million.

With nine floors and nearly 700 rooms, City Hall is the largest municipal building in the world. It is home to for all three branches of government, including the mayor’s office (executive branch), City Council (legislative), and a large part of the city and county judiciary. While the city and county of Philadelphia are separate political entities, they occupy the exact same acreage.

From 1894 until 1908, it was the tallest habitable building in the world. All of the previous buildings to hold this distinction—including Europe’s cathedrals and the Great Pyramid at Giza—had been religious; Philadelphia City Hall was the first secular building to bear that title.

Philadelphia City Hall was designated a National Historical Landmark in 1976 and a National Historic Civil Engineering Landmark, by the American Society of Civil Engineers, in 2006. It won 21st place on the American Institute of Architects’ list of America’s 150 favorite US structures, in 2007. It was nearly demolished in the 1950’s, but the cost of tearing it down would have bankrupted the city.