The Cap Stone above the entrance to the Magazine states it was built in 1873 in order to store gunpowder.
The Magazine was refurbished by Freddie Gomez after many years of lying unused. The premises is now used as a dance school.
The magazine was built on scree breccia, with an underlying bedrock of limestone. While it is generally considered likely that an earlier magazine was formerly on the same site. The current, British magazine dates back to at least 1873, based on the date inscribed on a keystone over one of the doorways. The Flat Bastion Magazine was constructed primarily of locally quarried limestone blocks. It was built in wartime to store approximately 5,000 barrels of gunpowder. Many of the original wooden supports for shelves/storage are still standing, which is unique in Gibraltar.
The main Magazine area was surrounded by a lighting passage, which created a corridor around the core area. There was also a shifting lobby, where people working in the magazine removed their clothing to eliminate the risk of sparks.
The doors, which are illustrated, were dated from oak that dates back five or six centuries, well before the British version of the magazine was built.