The South flank casemates at the Western Outworks of the Citadel were built as defensible casemated barracks, their small arms galleries serving to prevent an enemy force from gaining offensive positions in the ditch and on the counterscarp. They are positioned in the re-entrant where the South Flank meets the South Ditch. They are constructed against the rock-cut scarp face of the ditch, forming its revetment, in two ranges arranged at right-angles to one another (location accurate to the nearest 1m based on available information).