The chapel, which appears in its current position on the eastern quadrant of an older earthwork as early as the 1838 edition of the Ordnance Survey six-inch map, was built directly onto a ringfort, a type of circular enclosed settlement that served as the basic unit of early medieval rural life in Ireland. The result is an odd layering: Christian architecture rooted, quite literally, in prehistoric and early historic ground.

The ringfort at Tevrin is a platform type, meaning it occupies a raised, artificially levelled area on naturally undulating grassland, giving it a modest elevation above the surrounding terrain. Within and around its earthen bank, surveyors have identified traces of four possible hut sites, the low, square or circular outlines of domestic structures whose occupants would have lived, worked, and kept animals within the protected enclosure of the fort. There is also a possible collapsed souterrain, an underground stone-lined passage or chamber that typically served for storage or as a place of refuge, its roof long since fallen in. A stream running some thirty-five metres to the south marks the townland boundary with Killynan. One hut site of particular interest sits in the north-north-east of the interior, defined by a square earthen bank, and lies immediately to the east of another possible structure, suggesting a cluster of activity within what would once have been a busy domestic compound.