The east gable contains a late Romanesque window, a style of rounded, richly decorated stonework that flourished in Ireland during the twelfth century, and it is, by any measure, a remarkable piece of carving. Yet the more widely held view among architectural historians is that the window was not made for this building; it is thought to have been brought here from the nearby abbey. Alongside it sits a pointed arch doorway in the north wall, dated by Peter Harbison to around 1200, which raises its own questions about origin and reuse. The result is a building that reads, in part, like an anthology of stonework assembled from elsewhere, its true biography obscured beneath a heavy coat of later render.

The church itself is a rectangular structure, roughly 15.8 metres long and just over 6 metres wide, aligned east to west in the conventional medieval fashion. It sits at the southern end of a modern graveyard, about 75 metres from a structure known locally as the Nunnery. Earlier accounts, including those of Cochrane in 1901 and Fahey in 1904, refer to it as the Protestant or Church of England church, which suggests it remained in active use into the eighteenth century, long after much of the surrounding monastic complex had fallen into disuse. Some features, including two pointed arch windows in the south wall and a bell tower at the apex of the west gable, are thought to date from the seventeenth century or later. Scattered through the interior are cut-stone fragments, some of which may be twelfth or thirteenth century in date, adding yet another layer to the building's complicated chronology. An unexplained vertical line in the masonry of the north wall, near the east end, resists easy interpretation. Killanin and Duignan, writing in 1967, speculated that the present structure may itself sit over the footprint of an even earlier church, though the heavy rendering that coats the walls makes it difficult to verify anything with confidence.