The enormous city hall is still the tallest and largest masonry building in the world. Since no steel frame was used, the walls at the first floor are up to 22ft thick to support all the weight from the floors above. The eight floors, each about 16ft high, look like just three floors from the outside. The central tower reaches a height of 511ft. It is topped by a statue of William Penn. The massive statue is 37ft high and weighs 27 ton. It is just one of 250 sculptures created by Alexander Calder for both the interior and exterior of the city hall.