The building is modest in scale, around twenty-one metres from east to west and just six and a half metres across, constructed from sandstone and limestone rubble laid in rough courses with cut stone quoins at the corners. What makes it quietly arresting is the way its decay is uneven: the gables still stand, both smothered in ivy, while the west gable leans visibly outward, its masonry pulling away from the north wall in a slow, arrested collapse.

This was the parish church of Tullaghorton, and what survives of its architectural detail suggests a building of some refinement relative to its rural setting. The north wall retains the lower jambstones of a doorway near its west end, the stones cut with a double chamfer, a decorative moulding formed by two angled cuts that soften the edge of the stonework. The west gable holds a flat-headed single-light window with a chamfered surround and mixed limestone and sandstone jambs. More elaborate is the east gable, where a two-light ogee window survives within a round-headed embrasure that splays inward; the ogee form, with its shallow S-curved head, is typically associated with late medieval ecclesiastical building in Ireland. The central mullion that would have divided the two lights is gone, and elsewhere windows have been broken out of their embrasures entirely, leaving only partial splays and a tilting fragment of the south wall's window surround. The combination of what remains and what has been lost gives the ruin a quality of interrupted evidence, where the architectural ambition is legible but incomplete.