The Main Magazine at Fort Camden was of cut and cover construction and located adjacent to the casemates. It was linked by an underground tunnel to the Lower works. The Magazine has a single large chamber with lighting recesses and a lighting passage. The shifting room or lobby was at the base of the circular stairs up to the parade. The Main Magazine could hold 960 barrels of gunpowder.
An original Hobbs & Co lock survives in the magazine door. A famous London locksmiths who made quality locks.
The floor is wooden and in the corridor it is parquet flooring which appears to have be covered with bitumen.