The ruined abbey-church stands on a raised site, once an island in a peat bog. The 12C main doorway is finely carved and the chancel is in sandstone. The sacristy dates from the 15C or the 16C. The monastery was probably founded in the 6C by Saint Cainnech of Aghaboe, in County Laois, but it is also linked to Saint Cronan of Roscrea.