Neath Abbey (Abaty Nedd) was a Cistercian monastery, located near the present-day town of Neath in South Wales, UK. It was once the largest abbey in Wales. Substantial ruins can still be seen, and are in the care of Cadw. Tudor historian John Leland called Neath Abbey "the fairest abbey of all Wales."
Neath Abbey is also the name of an area of Neath near to the abbey ruins.
Neath Abbey was established in 1129 AD when Richard I de Grenville (d.post 1142), one of the Twelve Knights of Glamorgan, gave of his estate in Glamorgan, Wales, to Savigniac monks from western Normandy. The first monks arrived in 1130. Following the merging of the Savigniac order into the Cistercian order in 1147, Neath Abbey also became a Cistercian house. The abbey was ravaged by the Welsh uprisings of the 13th century.
During the Dissolution of the Monasteries by King Henry VIII of England the last abbot, Lleision ap Thomas, managed to buy time through payment of a large fine in 1536, bu