The opening is just thirty-five centimetres high and a little over a metre wide, and the passage beyond it extends for nearly three metres before being blocked by boulders. The roofing slabs sit almost flush with the enclosure's ground level, which gives the impression that the structure has been slowly swallowed by the earth around it. Whatever its original purpose, the engineering is deliberate and careful: the passage walls are neatly coursed with small slabs, and the whole arrangement suggests something more considered than simple shelter.

The wider enclosure at Cill Rialaigh is a substantial early Christian monastic complex, containing an oratory, three rectangular buildings, a cross-slab, and the corbelled hut itself with its associated passage. A cashel is a stone-walled enclosure, typically associated with early ecclesiastical or secular settlements in Ireland, and this one has walls substantial enough to have retained much of their form. Just outside the enclosure to the north sits a rectangular platform bearing a leacht, a type of commemorative stone cairn associated with prayer and remembrance at early Christian sites, alongside another cross-slab. The complex was used as a ceallúnach, an informal burial ground for unbaptised infants or others excluded from consecrated ground, right into the nineteenth century, which points to a long continuity of use long after its monastic function had faded. A holy well lies roughly ninety metres to the south-west, a further marker of the site's persistent sacred character. Scholars have disagreed about the passage's route: writing in 1902, Lynch argued it originally ran to the outer face of the enclosing rampart, while Henry, writing in 1957, proposed it turned to the south-east. Neither interpretation is now clearly supported by what survives on the ground, and the passage's precise function remains an open question.