Its south gable survives almost intact, carrying a flat-headed doorway and, above it, a single-light round-headed window of fifteenth-century date. The lower courses of the east and west walls, along with the north gable, are all that remain beyond that. What makes this building quietly interesting is precisely what nobody can agree on: whether it was ever a church at all.

Kilmacduagh is a monastic site of considerable age, traditionally associated with Saint Colman MacDuagh and dating in its origins to the early medieval period. The complex accumulated structures across many centuries, and this building sits at the edge of that accumulation. Peter Harbison, writing in 1975, catalogued it as a church of uncertain date, which is a reasonable enough classification given its form. But the building's alignment and the placement of its window have led some to suggest it was more likely a domestic structure connected to the adjacent abbey, perhaps a hall or lodging associated with the monastic community rather than a space for liturgical use. The round-headed window type is consistent with late medieval ecclesiastical stonework, but its position does not straightforwardly support a sacred function. The building measures roughly 13.3 metres on its longer axis and 5.3 metres across, dimensions that would suit a domestic range comfortably.

Visitors to Kilmacduagh will find the site dominated by its famous leaning round tower and the cathedral remains, and this small structure tends to go unnoticed nearby. It rewards a short detour, not for any drama in its appearance, but for the way it sits so patiently outside of easy classification, a remnant that even careful scholarship has preferred to leave as an open question.