Heritage Open Day: Medieval gatehouse, once part of Canterbury's city wall. Mainly used as the city prison. Open to the public with a prison exhibition and a fine city viewpoint on the battlements. The Westgate will be open without its usual admission charge. A climb of 34 stairs is necessary to reach the guardchamber - built in 1380 over what was the only road from London to guard the entrance into the city - where the museum exhibition is about the city defences. Having never been needed during the Hundred Years War, the building became the city prison in 1453, and the north drum-tower houses a prison exhibition. A further 27 stairs go up to the battlements viewpoint - once the exercise point for the prisoners - where there is an excellent view of the city of Canterbury.