Philadelphia architect Stephen Button designed the first building that was completed in 1847. It burned to the ground in 1849. In 1851, the present capitol, also in the Greek Revival style, was constructed on the previous building’s foundations.
Builder and industrialist Daniel Pratt may have helped a committee design the building. African American master carpenter Horace King executed much of the woodwork, including, most likely, the three-story spiral stairways that dominate the entrance hall.
The state has expanded the building three times: 1885 rear wing; 1906-1912 side wings; 1992 rear wing extension