The Tower has been (1) a fortress, and so it remains to the present day; (2) a palace, and (3) a prison. We can now consider it under these three aspects, merely mentioning in passing that it was also a mint, an armoury, and a record office.
_The Tower as a Fortress._--It was regarded as impregnable in the reign of Stephen, when it was specially required by the King as a fortress, and during the whole mediæval period it was always a place of strong defence. It does not appear ever to have endured a siege of any importance, but if it had, it would doubtless have successfully resisted attack.
The Byward Tower is the great gatehouse of the outer ward, and the Middle Tower is its outwork. There was formerly a drawbridge across the ditch or moat, where now there is a stone bridge 130 feet wide. The gateway to the Bloody or Garden Tower is the main entrance to the inner ward. The inner ward is enclosed within a curtain wall having four sides, twelve mural towers, and a gatehouse. Wakefield Tower, known also as the Record Tower and as the Hall Tower, is, in its lower storey, next in antiquity to the White Tower.
Commencing with Wakefield, and passing westward, the towers are Bloody (where the Duke of Clarence is supposed to have been drowned in Malmsey, and the two sons of Edward IV. smothered), Bell (so called from an alarm bell in the little turret), Beauchamp (from Thomas de Beauchamp, Earl of Warwick, and also called Cobham Tower, after Lord Cobham), Devereux (after Robert Devereux, Earl of Essex, also called 'Robyn the Devyll's Tower,') Flint, Bowyer (so called because it was the residence and workshop of the royal maker of bows), Brick (previously Burbidge), Martin (or Jewel, at one time styled Brick Tower), Constable's, Broad Arrow, Salt (meaning saltpetre; in the sixteenth century it was known as Julius Cæsar's Tower), and Lanthorn (called in 1532 the New Tower; it was pulled down in 1788, after a fire).
The wall of the outer ward has upon it bold drum bastions at the angles of the north front; and the south or Thames front is protected by five mural towers, of which one covers the landgate and one the watergate, and two others are connected with posterns. These towers are Develin (called 'Galighmaies Tower' in 4 Ric. II.), Well, Cradle, St. Thomas's (over Traitor's Gate), and Byward.