protect the City harbour in the south-east, and its outlines are still visible on the western wall of the present time fort. The harbour chain pulled across from the tower. The present time fort was completed in the 16th century, when the entire complex was enlarged and the outer wall extended up to the oldest tower level. The ground floor of St. Johns Fort houses the Aquarium, and the Maritime Museum is situated on the 1st and 2nd floor. One of the entrances to the walls is also situated here.