<P> A third ward was created during Edward I's extension to the Tower, as the narrow enclosure completely surrounded the castle . At the same time a bastion known as Legge's Mount was built at the castle's north - west corner . Brass Mount, the bastion in the north - east corner, was a later addition . The three rectangular towers along the east wall 15 metres (49 ft) apart were dismantled in 1843 . Although the bastions have often been ascribed to the Tudor period, there is no evidence to support this; archaeological investigations suggest that Legge's Mount dates from the reign of Edward I. Blocked battlements (also known as crenellations) in the south side of Legge's Mount are the only surviving medieval battlements at the Tower of London (the rest are Victorian replacements). A new 50 - metre (160 ft) moat was dug beyond the castle's new limits; it was originally 4.5 metres (15 ft) deeper in the middle than it is today . With the addition of a new curtain wall, the old main entrance to the Tower of London was obscured and made redundant; a new entrance was created in the south - west corner of the external wall circuit . The complex consisted of an inner and an outer gatehouse and a barbican, which became known as the Lion Tower as it was associated with the animals as part of the Royal Menagerie since at least the 1330s . The Lion Tower itself no longer survives . Edward extended the south side of the Tower of London onto land that had previously been submerged by the River Thames . In this wall, he built St Thomas's Tower between 1275 and 1279; later known as Traitors' Gate, it replaced the Bloody Tower as the castle's water-gate . The building is unique in England, and the closest parallel is the now demolished water-gate at the Louvre in Paris . The dock was covered with arrowslits in case of an attack on the castle from the River; there was also a portcullis at the entrance to control who entered . There were luxurious lodgings on the first floor . Edward also moved the Royal Mint into the Tower; its exact location early on is unknown, although it was probably in either the outer ward or the Lion Tower . By 1560, the Mint was located in a building in the outer ward near Salt Tower . Between 1348 and 1355, a second water-gate, Cradle Tower, was added east of St Thomas's Tower for the king's private use . </P> <P> Victorious at the Battle of Hastings on 14 October 1066, the invading Duke of Normandy, William the Conqueror, spent the rest of the year securing his holdings, by fortifying key positions . He founded several castles along the way, but took a circuitous route toward London; only when he reached Canterbury did he turn towards England's largest city . As the fortified bridge into London was held by Saxon troops, he decided instead to ravage Southwark before continuing his journey around southern England . A series of Norman victories along the route cut the city's supply lines and in December 1066, isolated and intimidated, its leaders yielded London without a fight . Between 1066 and 1087, William established 36 castles, although references in the Domesday Book indicate that many more were founded by his subordinates . The new ruling elite undertook what has been described as "the most extensive and concentrated programme of castle - building in the whole history of feudal Europe". They were multi-purpose buildings, serving as fortifications (used as a base of operations in enemy territory), centres of administration, and residences . </P> <P> William sent an advance party to prepare the city for his entrance, to celebrate his victory and found a castle; in the words of William's biographer, William of Poitiers, "certain fortifications were completed in the city against the restlessness of the huge and brutal populace . For he (William) realised that it was of the first importance to overawe the Londoners". At the time, London was the largest town in England; the foundation of Westminster Abbey and the old Palace of Westminster under Edward the Confessor had marked it as a centre of governance, and with a prosperous port it was important for the Normans to establish control over the settlement . The other two castles in London--Baynard's Castle and Montfichet's Castle--were established at the same time . The fortification that would later become known as the Tower of London was built onto the south - east corner of the Roman town walls, using them as prefabricated defences, with the River Thames providing additional protection from the south . This earliest phase of the castle would have been enclosed by a ditch and defended by a timber palisade, and probably had accommodation suitable for William . </P> <P> Most of the early Norman castles were built from timber, but by the end of the 11th century a few, including the Tower of London, had been renovated or replaced with stone . Work on the White Tower--which gives the whole castle its name--is usually considered to have begun in 1078, however the exact date is uncertain . William made Gundulf, Bishop of Rochester, responsible for its construction, although it may not have been completed until after William's death in 1087 . The White Tower is the earliest stone keep in England, and was the strongest point of the early castle . It also contained grand accommodation for the king . At the latest, it was probably finished by 1100 when Bishop Ranulf Flambard was imprisoned there . Flambard was loathed by the English for exacting harsh taxes . Although he is the first recorded prisoner held in the Tower, he was also the first person to escape from it, using a smuggled rope secreted in a butt of wine . He was held in luxury and permitted servants, but on 2 February 1101 he hosted a banquet for his captors . After plying them with drink, when no one was looking he lowered himself from a secluded chamber, and out of the Tower . The escape came as such a surprise that one contemporary chronicler accused the bishop of witchcraft . </P>

When was the tower of london built and by whom