 Casemate 11 was the main magazine for the redoubt, casemate 8 was modified in the 1870s as a cook house and casemates 23 and 24 were altered in the 1880s to provide a detention room and two cells.The upper tier above the casemates forms the terreplein or gun platform, which has a tall parapet pierced by granite-faced embrasures for eleven guns.Beside each gun position is an "L" shaped expense magazine which held a supply of ammunition for the guns to use in combat and could also be used as a shelter for the gun crews during an enemy bombardment.