Dipping its toes into the River Rosserk, this sublime Franciscan abbey dates from the mid-15th century. An eye-catching double piscina (perforated stone basin) is in the chancel: look for the exquisite carvings of a 2ft-high round tower (very rare to see one carved in this way) and two angels on either side of a Gothic arch.
The abbey is 4km south of Killala off the R314. Look for the signposts and then follow narrow farming lanes for another 5km.