 Built into this part of the wall is the stone Anglian Tower, which was once thought to have been built during the reign of Edwin of Northumbria, but now is generally thought to be of the very late Roman period.Behind the Anglian Tower are a series of banks showing the level of the defences during the Roman, early Middle Ages, Norman, and late medieval periods.The gardens contain several buildings dating back to the medieval period, most of them relating to St Mary's Abbey.