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. The low roof of these magazines forms a banquette or fire step so that the garrison could fire their muskets over the parapet in the event of an infantry attack. The parapet is also pierced by the main gate, which was originally the only access to the redoubt.