Charleston was one of the busiest slave-trading ports in the nation, funneling captives through the harbor for over a century. Public sales were originally conducted in the open air near the Old Exchange Building, but when the city outlawed outdoor slave auctions in 1856, the trade moved indoors to dedicated sale rooms. Ryan's Mart, a walled complex on Chalmers Street, became the city's primary indoor trading site; it now survives as the Old Slave Mart Museum, the only known building of its kind still standing in South Carolina.