As the largest city building in the United States, Philadelphia City Hall is a grand work of architecture. Its impressive size—it stands 548 feet tall and has 14.5 acres of floor space—is what makes it stand out. There are more than 700 rooms in the building.
Of course, a building this size would take a remarkably long time to construct—30 years to be exact. William Penn, the city’s founder, sits atop the building, and the tower’s observation deck offers 360 degree views of the city.