Already described as ‘ancient’ and ‘ruinated’ in 1622, the church’s surviving rubble walls and pinnings reveal a medieval structure that once measured roughly 13 metres by 5.5 metres internally. The eastern gable wall, rising to about 5 metres at its highest point, features a deeply splayed window built from small horizontally laid stones, whilst traces of an earlier, smaller window beside it suggest the building underwent modifications during its active life. The southern wall preserves evidence of another splayed window and the remains of a doorway with a relieving arch, though fire damage has left its mark on the inner masonry.

The modern graveyard surrounding the church contains several intriguing early features that hint at the site’s long sacred history. A 2.5 metre tall stone cross, carved from a single slab with distinctive hollowed angles and knob-like projections where the shaft meets the arms, stands south of the church ruins. Nearby, a smaller standing stone once supported what locals called the ‘wishing stone of Mevagh’, though this has since gone missing. Perhaps most remarkable is an irregularly shaped stone near the church’s southwest corner, its upper surface decorated with twenty-three clear cup marks; circular depressions about 6 centimetres wide and 1.5 centimetres deep that represent a form of prehistoric rock art.

The church’s position on the eastern edge of high, rocky ground offers commanding views across the steeply sloping cultivated lands down to Mulroy Bay. This strategic location, combined with the medieval architectural details and the presence of much earlier ritual markers like the cup-marked stone, suggests Mevagh has served as a sacred site for multiple cultures across millennia. The Archaeological Survey of County Donegal dates the surviving church fabric to the medieval period, though the site’s religious significance clearly extends much further back in time.