The medieval ruins of Llanthony Priory

Llanthony Priory is a partly ruined former Augustinian priory in the secluded Vale of Ewyas, a steep-sided once-glaciated valley within the Black Mountains area of the Brecon Beacons National Park in Monmouthshire, south east Wales. The priory dates back to around the year 1100, when one of Hugh de Lacy's knights called William reputedly came upon a ruined chapel of St. David at this location. He was inspired to devote himself to solitary prayer and study. He was joined by Ersinius, a former chaplain to Queen Matilda, and then by a band of followers. A church was built on the site, dedicated to St John the Baptist, and consecrated in 1108. By 1118, a group of around 40 canons had founded there a priory of Canons Regular, the first in Wales.

In 1135, after persistent attacks by the local Welsh population, the monks retreated to Gloucester, where they founded a secondary cell, Llanthony Secunda. However, around 1186 another member of the de Lacy family, Hugh, the fifth baron, endowed the estate with funds from his Irish estates to rebuild the priory church, and this work was completed by 1217. The Priory became one of the great medieval buildings in Wales, in a mixture of Norman and Gothic architectural styles. There was further building around 1325, with a new gatehouse. On 4 April 1327, the deposed Edward II stayed at the Priory on his way from Kenilworth Castle to Berkeley Castle.

During his journey around Wales accompanying the Archbishop of Canterbury Baldwin of Forde, Giraldus Cambrensis visited the priory in 1188 and wrote a description of the church of St. John. Following Owain Glyndŵr's rebellion in the early 15th century, the Priory seems to have been barely functioning. In 1481, it was formally merged with its daughter cell in Gloucester, but after 1538, both houses were suppressed in Henry VIII's dissolution of the monasteries. The main ruins are now under the care of Cadw, and entrance is free of charge to visitors.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons