The Parish and Priory Church of St. Mary was founded around 1072 as a Benedictine priory by William FitzOsbern and his son Roger de Breteuil. By the early 12th century, the monastic establishment had the status of an alien priory in its own right, though it probably never held more than about 12 monks. It superseded an earlier Augustinian priory located about 2 km away.
As Chepstow developed as a market town and port around the castle and priory during the medieval period, the nave became used as the parish church. Accommodation was built on the south side of the church, in the 13th century. The priory had extensive grounds, probably including most of the land south of the church enclosed by Chepstow's 13th-century town wall or Port Wall. The priory was eventually suppressed during the Dissolution of the Monasteries in 1536 during the English Reformation, at which time there were still three monks in residence. Most of the priory buildings, including the choir part of the church, the cloister, chapter house, lodgings and kitchens, were demolished at that time, and the foundations are buried beneath a car park beside the current church. Remains of a large barn and well were also found during excavations in the 1970s.
Part of the Norman church remains, but it has been greatly modified over later centuries. The original Priory Church was built in local yellow Triassic sandstone, with a long vaulted nave, massive piers, and a notably ornamented west entrance doorway with zigzag and lozenge patterns, dating from the early 12th century.
The main central tower of the original church collapsed in a storm in 1701, destroying the transepts. A new wall was then built at the eastern end of the nave, and its western end built up to form a new tower.
The church contains two fonts, one of Norman origin and the other from the 15th century. There are several notable tombs and memorials, including that of Henry Somerset, 2nd Earl of Worcester, and the Jacobean tomb of local benefactor Margaret Cleyton with her two husbands and 12 children.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.