The Powder Magazine's original roofing material is unknown, but by 1717 a slate roof was installed. Pan-tiling was replaced the slate years later. Its pyramidal roof is punctuated by gables on all sides. The arsenal's 32-inch thick brick walls and interior ceiling were constructed to both protect the gunpowder while also dampening a potential explosion. There is still sand in its attic today (2018).
After a new magazine was built in 1748, the structure likely did not house black powder until the outbreak of the Revolutionary War. Gunpowder was briefly stored at this location one more time in the 1820s while new state arsenals were being constructed. Throughout most of the 19th century, The Powder Magazine was utilized for miscellaneous storage, a printing house, a wine cellar, and a livery stable.
Since 1902, The Powder Magazine has been owned by the National Society of The Colonial Dames of America in the State of South Carolina (NSCDA-SC), which operates the property as a museum focused on interpreting South Carolina's 18th-century military history.