Powder Magazine

The Powder Magazine is a gunpowder magazine and museum in Charleston, South Carolina, USA and the oldest surviving public building in the former Province of Carolina. It was erected in 1713 by colonial settlers as a place to safely store and centralize their gunpowder supplies. It was also involved in the 1780 siege of Charleston. The Powder Magazine was declared a National Historic Landmark in 1989. It has operated as a museum since the early 1900s, although extensive renovations have since been conducted.
The National Society of the Colonial Dames of America is the current operator of the museum, which includes historic artifacts and displays about the building during the Colonial and American Revolution periods.
Each wall of the building boasts a large arch. The walls get thinner as they reach the top of the arch, changing from three feet thick, near the ground, to just a few inches thick near the top. There are also few doors in the building, so that in the event of an explosion, most of the explosive force would exit through the roof, with the arches acting like funnels. Sand stored in the roof would then smother and put out the fire.