As you enter the fort you are standing in the Advanced Battery named for the grouping of guns at the point, in advance of the main fort. The purpose of these guns was to protect the fort from an attack from the lake. It was, however, unlikely that an attack would come from the water. The guns situated in the Advanced Battery are on the highest point in the Kingston area (about 100 feet above the water) and could easily outrange any hostile Naval guns. Also, the Royal Navy's strong presence at the dockyard would likely discourage any Naval attack. A more likely route of attack would come from the north, overland. As a result the Fort's defences are oriented towards this threat.

The metal-roofed buildings on either side of the Advanced Battery were constructed later than the rest of the fort, from 1841 to 1843. In 1867, they were used as commissariat stores.