Apse chapel

It is reached generally by a semicircular passageway, or ambulatory, exteriorly to the walls or piers of the apse.

The eastern chevet of Westminster Abbey, surrounded by five apsidal chapels, is the only complete example of this feature in England.

[2] Each apsidal chapel could be treated as a sanctuary, to be entered only by the officiating, priest and his attendants, and the ambulatory served as the necessary nave for the worshippers.

In England, the apse chapel is very rare, owing to the generally square termination of the nave.

In continental churches the central apse chapel was often the Lady-chapel, which in England was generally placed at the side.