Annaghdown Abbey (full title: the Abbey of St Mary de Portu Patrum[1] but also commonly called Annaghdown Priory)[2] is a ruined house of the Arroasian canons in the townland of Annaghdown in County Galway, Ireland.[3] The site was probably founded by Turlough O'Conor c. 1140 and was dissolved after the reformation in 1562.[4] The remaining ruins include a church, a cloister and living quarters. Some details of the windows suggest that they were constructed in the 13th century while the south window of the choir is in the transitional style from c. 1200.[1]
As the east window itself appears to be missing and the east window of Annaghdown Cathedral, located 110 metres in a south-east direction, is of a similar period, it is possible that it was moved to the cathedral. Harbison, however, points out that the perfect fit of the east window of the cathedral does not make a late move likely.[1] The ruins of Annaghdown Abbey are a National Monument.[5]