Ceuta had been a naval base since Carthaginian and Roman times, and had some form of fortification since at least the 5th century. The city was captured by the Portuguese during the Conquest of Ceuta in 1415, who began to strengthen the defences in the 1540s by building the Royal Walls including bastions, a navigable moat and a drawbridge. Some of these bastions are still standing, like the bastions of Coraza Alta, Bandera and Mallorquines.