The Priory Church of St Mary is the parish church of Usk. Its origin was as the church of Usk Priory, a Benedictine nunnery founded by Richard de Clare, 2nd Earl of Pembroke in the twelfth century.
The site of the church shows no evidence of a pre-Conquest church, and the earliest religious building there may have been a Norman church associated with Usk Castle on the site of the present West nave. In the years before his death in 1176, Richard de Clare, 2nd Earl of Pembroke founded a Benedictine nunnery on the site. In the thirteenth century the North aisle was added as a place of worship for the people of the town, separated with a screen from the parts of the priory used exclusively by the nuns. In the fifteenth century, two two-storyed Perpendicular porches were added to the North and West aisles, the probable builder being Sir William Herbert, who was also building on a grand scale at nearby Raglan Castle.
After the Dissolution of the Monasteries in the late 1530s, the priory church became the parish church of the town. Extensive restoration and new building occurred in 1884 when Thomas Henry Wyatt created a sanctuary by roofing over the crossing space next to the tower and added a further bay to the nave. A further restoration was undertaken in 1899–1900, when G E Halliday inserted new windows and re-roofed the nave and aisle.
The gatehouse to the original Benedictine nunnery stands at the entrance to the churchyard.
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.