Of the towers of the so-called Outer Ward the principal are the Middle Tower, known also as the Martin Tower, forming the principal entrance, and giving access to a stone bridge across the moat, which replaces the ancient drawbridge, with the Bayward Tower at its further end, dominating the outer ward or ballium, and a narrow street running round the fortress itself; St. Thomas's Tower, with the Traitor's Gate opening on to the river, through which State prisoners were brought to the Tower; the cradle Tower, now merely a ruined vaulted gateway; the Wall Tower, the lower part of which alone remains; and the Develin or Iron Gate Tower, a modern erection, retaining some fragments of an ancient fortification of the same name.
At the south-east corner of the outer wall there was formerly a tower leading to an iron gate on the other side of the moat, and two strong ramparts which corresponded with this tower, called the Brass Mount and the Legge Mount, still exist at the north-east and west corners of the outer ward, completing its defences. The space between it and the inner ward was formerly almost entirely occupied by the buildings of the Royal Mint, which were removed in 1810.