According to tradition St Ronan and his daughter St Lasair established a church here on the banks of Lough Meelagh in the 6th century. The present church ruin, which dates from the 14th century, was built by the O’Duignan family. The romanesque doorway on the south side may date from an earlier 12th century church.
Peregrine O’Duignan (a member of the O’Duignan Clan) was one of the Four Masters, who were the authors of The Annals of Lough Key, - a history of Connacht and neighbouring regions from early times up to the 17th century.
As can be seen from the ruins, local stone was used in the building and wheaten straw was used for roofing. The structure was burned down twice and was rebuilt on both occasions.
On the northern side of the church is a crypt belonging to the McDermott Roe family. This is where Turlough O’Carolan, the last of the Irish Bards, is buried.
The Abbey was used by monks, one of whom is buried within the ruins. Details of his death are carved on a large flagstone which is still inside the Abbey wall.