Nothing can now be seen of the remains of the medieval abbey. As a result of excavation and geophysical examination, archaeologists are now happy that the final site was on the east bank of the Troddi river.
Grace Dieu was always a small, poor house. It was founded quite late, in 1226, with a nucleus of monks from Abbey Dore. The original site was probably on the west bank of the Troddi, at or near the modern house called Parc Grace Dieu. There was not enough unoccupied land in the area to support a community, and the monks were given land which already belonged to the local Welsh. The abbey was destroyed by the Welsh during a raid by Llywelyn ab Iorwerth, king of Gwynedd, in 1233, and the monks were forced to take refuge at nearby White Castle. The abbey was re-established in 1236, probably in its final location (on the east bank of the Troddi, within easier reach of the English centre of Monmouth).
Because of its poverty and remoteness, the abbey was perhaps closer to the Cistercian ideal than its wealthier and better-known fellows.
More details on the Monastic Wales site at http://www.monasticwales.org/site/28 .