This fortified church at Clonmines, County Wexford, sits at the eastern edge of the graveyard of the parish church of St. Nicholas, about 170 metres from the western bank of the Owenduff/Corock river. It survives remarkably intact, rising to its full stepped battlements, all dressed in granite, in a landscape defined on most sides by earthen banks and trees rather than the more expected masonry enclosure.

The building is small but architecturally dense. The single rectangular cell, measuring roughly 8.4 metres by 4.7 metres internally, is roofed in two different ways: a barrel-vault covers the western portion, while a groin-vault, formed by two barrel-vaults intersecting at right angles, covers the chancel to the east. The main doorway in the west wall is protected by machicolation at the parapet level, a feature more common to castles than parish churches, where it allowed defenders to drop material on anyone attempting to force an entry. A second, narrower doorway in the north wall is accompanied by an arched recess in the outer wall face that may have served as an ossuary, a temporary resting place for disinterred bones. Inside, a water stoup has been removed from beside the west entrance, a piscina (the small stone basin used for draining water after the washing of sacred vessels) is also gone, but a plain aumbry, a recessed cupboard for storing liturgical items, remains at the east end of the south wall. Three consecration crosses, incised into the wall plaster during the original dedication of the building, are still faintly present. A newel stair at the north-west angle climbs first to a gallery over the west end of the nave, then continues to a rooftop look-out platform. At the north-east angle, a D-shaped two-storey turret contains a small corbelled chamber at its base, just over a metre across, which the antiquarian George Victor Du Noyer, writing between 1864 and 1866, identified as an oven. Later interpretation has suggested it may simply be a structural solution to match the height of the turret to its companion at the north-west without loading the stonework with excess solid masonry. An opening in the west parapet, which could have been reached by ladder from the ground, was once read as an entrance but may instead have been a bellcote for a hanging bell.