A National Historic Landmark constructed in 1827 and believed to be the oldest building of fireproof construction in the United States. The work of Robert Mills, the first native-born American to be trained as an architect, and a Charleston native who worked with other important early American architects such as Thomas Jefferson and Benjamin Latrobe. Mills was responsible for the Washington Monument and many other public buildings. The building consists primarily of solid masonry in a simple Greek Doric style. An oval hall contains a cantilevered stone staircase lit by a cupola. The building serves as the headquarters for the South Carolina Historical Society, a private non-profit organization founded in 1856.