The Powder Magazine is a gunpowder magazine and museum at 79 Cumberland Street in Charleston, South Carolina, USA. Completed in 1713, it is the oldest surviving public building in the former Province of Carolina. It was used as a gunpowder store through the American Revolutionary War, and later saw other uses. The Powder Magazine was declared a National Historic Landmark in 1989. It has been operated as a museum by the National Society of the Colonial Dames of America since the early 1900s. It was designated a National Historic Landmark in 1972.