The Cistercian abbey of Knockmoy was founded by Cathal O’Connor, the King of Connacht, in 1189-90. O’Connor was later buried in the abbey in 1244.
The abbey at Knockmoy is unusual in that it has a fresco visible (barely) on the wall of the chancel, probably dating from around 1400. In 1200, the monastery was captured by William De Burgo.
Unusually, in 1440, the Abbot of the monastery was censured as he allowed his hair be washed by a woman. He was later accused of setting fire to the abbey in 1483. The remains consist of a church nave, chancel, transept and two chapels.