Saint Catherine's Fort

Saint Catherine's Fort is a marine fort built of rock-faced limestone with tooled limestone dressings and some granite. It is aligned northwest to southeast and features a two-storey entrance with a basement at the northwest end. The centre of the fort has three large square gun openings in granite-faced walling on each side, and the southeast end has a trilobe bastion that serves as an open-air gun platform. The fort is topped with a prominent rounded cornice and a low parapet, with a similar rounded moulding over the basement at the entrance end.

The entrance is accessed across a dry moat, which originally had a drawbridge leading to a rusticated arched entry. This entry features oversized radiating voussoirs, a plaque above, and corbelling under the cornice. On the ground floor, there are square-headed gun openings on each side, positioned at angles to the projecting square bastions. These bastions have similar openings on the basement and ground floor, along with small cambered-headed windows on the first floor. The side walls contain three square recessed small gunports on each of the three levels, allowing for command over the dry moat. The lower levels of the side walls are granite faced, featuring curved jambs and massive voussoirs to the gun openings, which are now glazed, while the upper parts are constructed of grey stone walling. The end bastions are low, as they are built into the rising rock.

The fort has not been inspected recently and is reported to be much damaged.