Exchange and Provost Building, Colonial museum in Charleston, United States.

The Old Exchange & Provost Dungeon, also called the Custom House, is a two-story masonry building at East Bay and Broad Streets, built 1767–1771. It has a hipped roof with cupola on a high brick basement. The west facade centers on a projecting three-bay gabled section with three round-arch entrances and Ionic pilasters above; flanking walls have Palladian windows with balustrades.

South Carolina's provincial government built the Exchange between 1767 and 1771 as a custom house, market and meeting place. In 1774 confiscated tea was stored here, and the revolutionary councils met in the building. After the British took Charleston in 1780 it became a barracks, with prisoners held in the basement; a 2012 study documented at least 120 of them, including some British soldiers.

The building housed South Carolina's 1788 convention to ratify the U.S. Constitution, and George Washington was greeted by a crowd on its balcony during his week-long stay in Charleston. Costumed guided tours now cover all three floors, and docents lead personal dungeon tours in place of the former animatronic pirate figures.

The museum sits near the waterfront in a walkable area with other historic sites nearby, making it convenient to visit as part of a broader tour of Charleston's colonial past. Wear comfortable shoes and allow time to explore both the main hall upstairs and the cellars below, as each space tells part of the story.

In 1965, the Half-Moon Battery, a fortification built in 1698, was found beneath the building. A 2012 study of the basement's wartime use documented at least 120 prisoners held in the Exchange, though many more could not be identified, and some of them were British soldiers.