"P" is for Powder Magazine (Charleston). In 1703 the colonial assembly authorized the construction of a storehouse for gunpowder as part of the defenses of Charleston. The Powder Magazine was built on the northern edge of the walled city in 1713. The one-story brick structure has a pyramidal tile roof with cross gables and a single room measuring approximately twenty-seven feet square. The walls are thirty-six inches thick. The National Society of the Colonial Dames in South Carolina purchased the building in 1902 to save it from demolition—and turned it into a museum. In 1993, the Historic Charleston Foundation leased the property; restored it; and reopened the building as a museum of early Charleston history. Currently located at 21 Cumberland Street, the Powder Magazine is considered the oldest surviving building in the Carolinas.