As if the subject of slavery wasn't dark enough, the sense of horror is heightened by knowing that this building, constructed in 1859, is the last surviving slave auction gallery in South Carolina. Telling the story of Charleston's role in the inter-state slave trade from 1856 to 1863, it has been operating as a museum on and off since 1938 and even today members of staff can trace their history to Charleston slaves.
If you go:
This is very much an educational place rather than an interpretive experience: expect informative, very detailed posters rather than artifacts. For this reason the museum advises that children are unlikely to find a visit entertaining.
Links:

6 Chalmers Street
Charleston, South Carolina 29401 USA
Phone Numbers:
+1 (843) 958-6467