In the graveyard at Harristown, a rectangular limestone ruin sits so thickly wrapped in ivy that the vegetation has become almost structural, holding together walls that have otherwise been reduced to their lowest courses. The building measures roughly 18.7 metres east to west and 6.3 metres north to south internally, a substantial footprint, though most of the north wall and the eastern portion of the south wall survive only as rubble footings. The gable walls at each end have been partially robbed out, their stone taken for use elsewhere at some point, as happened to countless rural churches across Ireland when building material was scarce and history was less protected than it is now. No windows appear to remain intact.

What the ruin does preserve is an entrance in the south wall, set towards the western end, with a two-centred limestone surround recessed into the external face. A two-centred arch, sometimes called a pointed arch, is the form most associated with Gothic ecclesiastical building, where two arcs meet at a slight point rather than forming a full semicircle. Inside the threshold, traces of a large wooden lintel survive, a detail that is easy to overlook but speaks to the practical layering of materials that characterised smaller Irish parish churches. Within the interior, a font remains in place, a baptismal basin that would once have been the functional heart of the building's sacramental life. A small burial plot from the nineteenth century presses against the outer face of the west gable, and modern burials have continued inside the ruin itself, meaning the site remains an active graveyard rather than simply an archaeological remnant.