Known locally as the abbey church, it was actually the parish church, the place where ordinary congregational life was conducted, yet its architecture tells a more complicated story than simple parish use would suggest. Tucked into a shelf on a north and east-facing slope, with a stream running nearby to the east, the building is rectangular and relatively modest in its footprint, measuring roughly nineteen metres east to west and five and a half metres north to south. What makes it unusual is the barrel vault at its western end, a curved stone ceiling of a kind more often associated with defensive building than with pastoral worship, and the evidence suggests that is exactly what it was meant to support: a tower providing fortified accommodation above the vaulted space.

The internal arrangement rewards close attention. A mural stair, built into the thickness of the dividing wall, rises to the first floor over the vault, suggesting a structure designed for retreat as much as for liturgy. At ground level, a corridor ran along the outside of the southern wall, and doorways pierced both the north and south walls at their centres. Light came through two small windows in the north wall and through cusped ogee-headed windows at the east and west ends, the ogee arch being a late medieval form with a gentle S-curve, widely used in Irish ecclesiastical building from the fourteenth and fifteenth centuries. After 1471, the church was counted among the churches of the rectory of Muinter Eolais, the Gaelic lordship that held this part of Leitrim, placing it within a specific administrative and territorial context at a time when the boundary between ecclesiastical and secular power was rarely clean. The larger church in the same complex, positioned about 130 metres to the south-west, shares with this one the status of National Monument, along with the surrounding earthworks.