Fort Sumter is a sea fort in Charleston, South Carolina, notable for two battles of the American Civil War. It was one of a number of many special forts planned after the War of 1812, combining high walls and heavy masonry, and classified as Third System, as a grade of structural integrity. Work started in 1829, but was incomplete by 1860, when South Carolina seceded from the Union. It is open for public tours as part of the Fort Sumter National Monument operated by the National Park Service.