Clare Abbey, Augustinian monastery ruins near Ennis, County Clare, Ireland

Clare Abbey is a ruined Augustinian monastery on the west bank of the Fergus, built of grey rubble masonry. Its square belfry tower has a crenellated parapet with corner battlements and narrow slit windows. The church, a long nave and chancel divided by the tower, measures about 39 by 9.5 metres and retains three fifteenth-century traceried windows. Domestic buildings and a cloister lie south and east of the church.

Clare Abbey was founded in 1189 by Domnall Mór Ua Briain, king of Thomond, as the Abbey of St Peter and St Paul at Kilmony, for Augustinian Canons Regular. In 1278 Donallbeg O'Brien ambushed and massacred Mahon O'Brien and his followers quartered there. After the dissolution of the monasteries in 1543, Henry VIII granted the abbey and lands to the Barons of Ibrackan; monks seem to have stayed until about 1650.

The abbey's original name was the Abbey of St Peter and St Paul at Kilmony; Kilmony means "the church on the bog". A bullaun in a block of granite and a stone carving over one window may survive from an earlier church on the site. The canons were Italian priests following the rule of St Augustine, working in parish care.

The site is located roughly 1 mile (2 kilometers) north of Clarecastle and remains accessible to visitors wishing to explore medieval ruins. Sturdy footwear is recommended as the ground is uneven and the riverside location can be damp, especially after rain.

The ground sits in a flood-prone area, where rising water occasionally transforms the ruins into an isolated landform. These episodes create a striking contrast between the ancient walls and the modern landscape surrounding them.