Pressed against a natural scarp at the northern edge of a broader enclosure, the structure is small even by the modest standards of early Irish ecclesiastical architecture, and a modern field wall has been built directly over its eastern end-wall, half-burying what survives beneath the everyday workings of a later landscape.

The oratory measures just 3.6 metres east to west and 2.8 metres north to south internally, making it barely larger than a modest room. Its walls are drystone and corbelled, a construction technique in which stones are laid in horizontal courses that project slightly inward with each layer, allowing a roof to be formed without mortar or timber. Those walls, averaging 1.1 metres thick, are built from dressed slabs laid in careful horizontal courses with smaller pinning stones filling the gaps. They survive to a maximum height of only 0.9 metres at the south-west angle. A large gap in the south wall may be the result of collapse or later disturbance, while a narrower opening on the west side, roughly 0.7 metres wide, is the probable location of the original doorway. On the south side of the building, a raised area roughly 2 metres wide is edged with upright slabs and patches of drystone revetment, a low platform of unclear purpose that adds a further layer of quiet strangeness to the site. The name Cill Buaine itself follows the pattern of early Irish ecclesiastical place-names, where "cill" denotes a church or monastic cell, suggesting a foundation of some antiquity, though the precise history of who built here and when remains unrecorded.