Early documents refer to it as both Killhunsin and the white church, the latter eventually winning out and attaching itself to the whole surrounding area. The building sits on a prominent rise above the countryside, occupying the north-west corner of a walled graveyard, and its gables still stand to their full original height, which is far from a given with ruins of this age.

The church was confirmed to the Abbey of St. Mary's in Dublin in the early thirteenth century, folding it into the network of Cistercian holdings that spread across the medieval Irish countryside. It appears on the Down Survey maps of 1655 to 1656, the ambitious cartographic project commissioned under Cromwellian administration to record land ownership across Ireland, which at least tells us the structure was still considered significant at that point. The building is constructed of randomly coursed granite masonry, meaning the stones are laid without strict horizontal rows, a technique common in early Irish ecclesiastical building. It follows the standard two-part plan of nave and narrower chancel, with the nave measuring roughly nine metres long internally and the chancel around six and a half. Entry is through a round-arched doorway with chamfered jambs, set into the west end of the north wall rather than the more typical west gable position. Inside the nave, two narrow slit openings admit light, and the nave connects to the chancel through a pointed segmental arch. A large plain rectangular opening punctuates the east gable.

The church sits within its walled graveyard, which remains the most practical point of orientation for a visitor. The granite construction weathers to a particular pale grey in certain lights, which may help explain the old association with whiteness that runs through both recorded names. The slit openings in the nave are worth examining closely as examples of how early medieval builders managed light in small stone structures. The east gable opening, larger and more plainly cut than the others, has a different character entirely, and its purpose or date relative to the rest of the fabric is not entirely clear from what survives.