Cirencester Abbey or St Mary's Abbey, Cirencester in Gloucestershire was founded as an Augustinian monastery in 1117 on the site of an earlier church, the oldest-known Saxon church in England, which had itself been built on the site of a Roman structure. The church was greatly enlarged in the 14th century with addition of an ambulatory to the east end. The abbot became mitred 1416. The monastery was suppressed in 1539 and presented to Roger Bassinge.
In the twelfth and thirteenth centuries, the abbey fostered the successful writers Robert of Cricklade and Alexander Neckam. They were supported in their work by other canons, including Walter of Mileto and Alexander's nephew Geoffrey Brito.