The Cistercians were a reform-minded monastic order who favoured remote, well-watered lowlands for their houses, and Inishlounaght fitted that template precisely. What makes this particular spot unusual is the layering: a dissolved medieval monastery, a ruin that persisted for over a century after suppression, and finally a Victorian church built directly on top, with fragments of the earlier structure absorbed into the new one rather than carted away or forgotten.

The abbey was founded in 1148 as a daughter house of Mellifont, the first Cistercian foundation in Ireland, though its affiliation was transferred to Monasteranenagh just three years later. In 1187 it received fresh patronage from two notable figures: Malachy O'Phelan, Prince of the Decies, and Donal Mor O'Brien, king of Limerick, who together re-endowed the monastery. At its height, Inishlounaght was itself a mother house, with daughter foundations at Fermoy in Cork, Corcomroe in Clare, and Glanawydan in Waterford. By 1467, though, the buildings were already in need of repair, a sign of the slow institutional decline that preceded the Dissolution. The monastery was suppressed in 1540, and the following year a jury reported that the church could be demolished, with the remaining buildings made available to a farmer named Thomas Butler. Despite this verdict, the walls were still standing in the mid-seventeenth century, recorded in one survey as "the walls of an old Aby", and as late as 1746 the church was described simply as "in ruins".

The Church of Ireland building that now occupies the site contains several fragments of the medieval abbey worked into its fabric, and a medieval graveslab is embedded in the floor at the threshold of the inner west door, visible to anyone who enters. Carpet laid along the centre aisle could not be lifted at the time of survey, and there may be further fragments beneath it. Early graveslabs also survive in the surrounding graveyard. Above ground to the south of the church there is nothing obvious to see, and the field to the north has been tilled. A lidar survey carried out by researchers from UCD between 2006 and 2010 told a more complex story, however, detecting earthworks south of the graveyard that probably relate to the abbey complex, along with rectangular plots to the north that appear to form part of a pre-1700 settlement cluster, all of it invisible to the casual eye but present nonetheless, just beneath the surface.