The shape is almost circular, roughly five metres across, and it sits just north of the centre of the enclosure. A cashel is a dry-stone ringfort, a type of enclosed settlement common across early medieval Ireland, and the one at Cill Éinne contains this hut as one of its interior features. What makes the structure quietly interesting is not its size but the questions embedded in its walls.

The foundations are double-faced, meaning an outer stone face and an inner stone face with a rubble core between them, and they survive to a height of only about twenty centimetres. The wall is 1.6 metres wide, which is substantial for a structure of this scale. Along the southern section, an additional line of foundation stones is visible running between those two faces. This either suggests the wall was originally built narrower at that point and later thickened, or that it was reinforced at some stage after construction. Whether this reflects a change in how the building was used, a repair after damage, or simply a decision by the original builders to strengthen one side, cannot be said with certainty from what survives. Gaps in the foundations on the east and west sides may mark where doorways once stood, though the evidence is fragmentary.