Its drystone walls are so unremarkable in their construction that they are effectively indistinguishable from the field walls surrounding it, giving no immediate signal that this is Cill Dubh, an early ecclesiastical site whose Irish name translates roughly as "the dark church". The uneven interior, with its mounds and terraces, looks like rough ground, and in fact appears to be entirely natural in origin, the hillside simply doing what hillsides do. Yet children were still being buried here as late as the nineteenth century, a practice common in Ireland at sites associated with early Christianity, where the ground was considered sanctified even when no formal church structure survived.

The most significant feature of the enclosure is a carved cross-slab standing near the south-east corner, just over a metre tall and some thirty-six centimetres wide. On its south-west face, an equal-armed cross has been carved within a circle, with a small saltire cross, that is, an X-shaped cross, filling each of the four quadrants formed by the circle and the arms. Below the circle, the lower arm of the main cross continues downward and appears to end in a scroll or pelta-like motif, a curved decorative form occasionally found in early medieval Irish stonework, though this detail is now only faintly visible. The opposite face of the slab carries a simpler equal-armed cross with no surrounding ornament. Nearby, two stones set upright on their edges and a large flat slab lying on the ground occupy the area to the west and south of the cross-slab, though what purpose they originally served remains unknown.