Clare Abbey is a ruined Augustinian monastery located about a mile north of the Clarecastle in County Clare, Ireland. The abbey was founded in 1194 under the sponsorship of Donal Mór Ua Briain (Donald O'Brien), the king of Thomond. The ruins include a church and cloister with ranges of domestic buildings to the east and south of the garth, and a gateway and enclosures. The church was originally a long oblong building, 39 metres by 9 metres 40 centimetres, externally. The interior was subsequently divided into a nave and chancel by a belfry tower 4 metres 80 centimetres, and the chancel 14 metres 75 centimetres.