The majority of the buildings within the Detached bastion are Captain Du Cane’s work of the early 1860s, though all were modified in the 1890s, and are constructed in stock brick laid to English bond. The expense magazine is a sunken building approached along a short covered way from the troop shelter. The structure was radically altered during the 1890s but retains some work of the early 1860s. (location accurate to the nearest 1m based on available information)