Remnants of Llanthony Prima
Nothing survives of the first church which was built in the early twelfth century, but there are substantial standing remains of its successor that dates from the late twelfth century. Rebuilding was probably carried out from c. 1180 to 1230. The church was transitional in style, blending Gothic pointed arches with Norman rounded ones. It was cruciform in design having an impressive crossing tower. This evidently had a simple clock from about the late fourteenth century. The south and west walls of this tower still stand but the upper storey is missing. There were two other towers at the west end of the church and the building was aisled, with a chapel leading off from each transept on the east. The south transept is the better preserved of the two and the large window openings are intact. In the fourteenth century the north transept and its chapel were converted for domestic use. There are substantial remains of the nave and the eight bays of the arcade (see image) of the north aisle still stand. The triforium above with its paired lancet windows in round-headed openings is partly ruined. The clerestory windows have not survived. The exterior of the west end indicates just how impressive the medieval building was. The great west window survived until the early nineteenth century. It had three tall lancets which extended to the height of the towers, with three smaller lancets above.
Little remains of the former claustral buildings. Part of the stone-vaulted chapter-house (see image) survives on what was the east range. The south-western tower of the church and the north part of the western range are now part of a hotel. It is thought that the parish church to the south of the ruins and perhaps also the adjacent farmhouse occupy the site of the former infirmary and its chapel.
The area of the outer court is marked by remains of the precinct walls and what was formerly the great gatehouse. This was adapted for use as a barn following the Dissolution but some medieval features survive including a thirteenth-century window in the Early English style and two fourteenth-century cusped windows. The outer court may have been used as a warren following the suppression of the house.
To the west of the complex are remnants of fish stews, a dovecot lies to the south and south-east and a mill to the south-west is thought to occupy the site of the medieval mill. 
 O. E. Craster, Llanthony Priory (1963); Coflein database]
Monastic sites related to this articleLlanthony Prima, Monmouthshire(Priory)