The roofless shell of a Church of Ireland parish church, built in 1830, stands on the northern side of the graveyard, and immediately to its south lie the earlier remains of a medieval church. Two abandoned buildings, centuries apart in origin, occupying the same small ground.

The 1830 structure was designed to accommodate 150 people, a modest congregation even by rural Irish standards of the period. Constructed from roughly coursed sandstone with cut stone detailing, it follows a rectangular plan oriented roughly west-southwest to east-northeast. The south wall carries three pointed windows fitted with hood mouldings, the kind of projecting drip-course carved above an opening to throw rainwater clear of the stonework; the central window is noticeably larger than the two flanking it. Two further windows sit in the north wall. At the eastern end of that same north wall is a small vestry, and on the west gable rises a tall two-storey tower with corner buttresses and a flat-headed door opening, also with a hood moulding, set into its south face. The building is now roofless, its dressed stonework open to the sky.

The presence of the medieval church immediately to the south suggests this was an established place of worship long before the nineteenth-century structure was raised beside it. That pattern, of a post-Reformation or later church built in close proximity to an older ruin on the same site, is not uncommon in Ireland, where continuity of sacred ground often outlasted continuity of congregation or creed. At Marshalstown, the two ruins sit close enough together that the decision to build where they did in 1830 was almost certainly deliberate, a new parish church planted at the edge of something much older.