In the grounds of the peaceful Museum Gardens, you can see the Multangular Tower, a part of the City Walls that was once the western tower of the Roman garrison's defensive ramparts. The Roman stonework at the base has been built over with 13th-century additions. On the other side of the gardens are the ruins of St Mary's Abbey dating from 1270 to 1294. The ruined Gatehall was its main entrance, providing access from the abbey to the river.
The adjacent Hospitium dates from the 14th century, although the timber-framed upper storey is a much-restored survivor from the 15th century, used as the abbey guest house. St Mary's Lodge was built in about 1470 to provide VIP accommodation.