The interior of the brick Fort Barrancas is a bit unusual in that it has no parade ground. It is filled with earth that slopes upward from the sally port toward the front gun positions and has no flat area for buildings or a parade. This arrangement made it impossible to house a significant number of troops within the walls of the brick fort and necessitated a separate cantonment area for housing and support. This separate area, located on the left flank of the old fort, came to be known as Barrancas Barracks but had a number of other names. The Barrancas Barracks served as the headquarters and support area for the four Third System forts: Fort Pickens, Fort McRee, Fort Barrancas and the Advanced Redoubt. The forts were rarely garrisoned in peacetime and Barrancas Barracks maintained a minimum number of men who could garrison the forts if needed.