The battlemented parapets running along the top of the chancel walls sit oddly above stonework that began its life as a simple early Christian oratory, and the effect is quietly dissonant in a way that photographs rarely capture.

The earliest phase is the oratory itself, a modest east-west structure measuring roughly 5.7 metres long by 4.4 metres wide. It has antae, the projecting end-walls characteristic of early Irish stone churches, and a trabeate doorway at the west end, meaning the opening is formed by two upright stones with a flat lintel laid across rather than a true arch. At some later point a chancel was added to the east, its arch inserted between the original antae, effectively threading the new construction into the bones of the old. Later still, battlemented parapets were raised on the north and south walls of that chancel, giving the building an incongruously fortified upper profile. A transitional east window in the chancel, mixing Romanesque and Gothic elements, adds another layer to this palimpsest of construction. On the outer face of the wall at the north-west corner there is a slab carved with an animal motif, the kind of detail easy to walk past without noticing. The site is known locally as Teampall Mac Duach, a name connecting it to Saint Colman Mac Duach, the seventh-century founder associated with the nearby monastic complex at Kilmacduagh on the mainland in County Galway.

The church does not stand alone. A cross-inscribed pillar rises to the west, a plain pillar-stone stands to the north, and a holy well lies to the south-south-west. A holy well in this context would have functioned as a site of local devotion, often associated with the patron saint of a nearby church, and patterns or rounds of prayer were sometimes performed at such wells well into modern times. There is also a possible souterrain in the vicinity, an underground stone-lined passage typically associated with early medieval settlement, though its extent and purpose here remain uncertain. The whole cluster sits roughly 180 metres north-west of the larger Teampall na Naomh, and the proximity of these monuments to one another suggests this part of Cill Mhuirbhigh on Inis Mór was a place of sustained significance across many centuries.