Aberconwy Abbey was a Cistercian foundation at Conwy, later transferred to Maenan near Llanrwst, and in the 13th century was the most important abbey in the north of Wales.
A Cistercian house was founded at Rhedynog Felen near Caernarfon in 1186 by a group of monks from Strata Florida Abbey. About four or five years later they moved to Conwy, and in 1199 were given large grants of land by Llywelyn the Great who had recently become ruler of Gwynedd. Llywelyn was regarded as the founder of the house, and thanks to his support it came to hold more land than any other Welsh abbey, over 40,000 acres (160 km²). On Llywelyn's death in 1240 he was buried at the abbey, and his son and successor Dafydd ap Llywelyn was also buried here in 1246. In 1248 Llywelyn's other son, Gruffydd ap Llywelyn, who had died trying to escape from the Tower of London in 1244, was reburied at Aberconwy after the abbot of Aberconwy, together with the abbot of Strata Florida, had arranged for his body to be repatriated from London.