Cairn, Bíofán, Co. Donegal

The complex consists of a substantial circular stone enclosure, measuring 18.3 metres across internally, with walls that were originally about 1.4 metres thick. Though time has weathered the structure, stretches of the wall facing remain visible both inside and out, with a deliberate gap of 2.3 metres on the southern side serving as the entrance. A curious semicircular kink in the eastern wall appears to be an original architectural feature rather than later damage.

At the heart of the enclosure stand the ruins of St. Columbkille's Chapel, a modest structure measuring roughly 5.75 metres north to south and 3.4 metres east to west internally. The church walls, built from mortared slab stones with carefully cut ashlar corner stones, are 0.75 metres thick, with the northeastern corner particularly well preserved. The main entrance sits centrally in the eastern wall, surrounded by several reused cut stones. Inside the northeast corner lies a peculiar feature known as St. Columbkille's Bed; two horizontal stone slabs bordered on the south by three upright stones, with a small alcove above it in the eastern wall. This alcove, measuring 35 by 20 centimetres and equally deep, plays a role in the traditional turas, or pilgrimage circuit, associated with the saint.

The enclosure also contains several cairns topped with inscribed cross slabs, silent witnesses to centuries of devotion. The largest cairn in the southeast supports two cross slabs, one bearing faint geometric designs between its arms, whilst another cairn to the northeast displays a simple incised cross on its western face. Outside the enclosure to the east sits a mound crowned by a large natural boulder known as Leac Na mBonn, or 'flagstone of the footsoles', inscribed with a cross within a circle, its arms extending just beyond the circumference to end in distinctive T shaped terminals. These various monuments, scattered across what is now fair pasture land, create a complex religious landscape that has drawn pilgrims and visitors for generations.