This tower was built in 1040 and is renowned as being Oxford's oldest building on record. The tower itself is attached to Bocardo Prison where it is thought that the bishops Latimer, Ridley and Cranmer were said to be burned by order of Queen Mary. The first floor of this building exhibits original church silver dating from this period, including an Elizabethan chalice which dates from 1562. The old accounts from church wardens are kept here and are available for viewing. The tower is open from April to October and again from November to March.