The Old Slave Mart Museum. Believed to be a privately owned slave auction house in operation during the 1830's to the 1850's.
Nowadays, tourists visiting Charleston often mistake the City Market (at another location) as the place where slave auctions occurred; in reality, it was where slaves and farmers alike went to sell their goods.
This is said to be an actual auction house. Many people do not realize that 35%-40% of slaves entering the US during these times entered through Charleston.