It is an oratory, a small early Christian place of worship, built in the drystone method, meaning no mortar was used, the walls held together entirely by the careful placement of coursed stone around a rubble core. What makes it quietly arresting is not its size, which is modest at 4.6 metres by 2.7 metres internally, but what it contains: up to ten uninscribed upright slabs arranged in the western half of its interior, their plainness and positioning suggesting the building served as a ceallúnach.

A ceallúnach is an early medieval burial ground for unbaptised infants or others excluded from consecrated burial, typically located at the margins of settled or sacred space. These sites are found across Ireland and carry a particular weight in the landscape, often marked by small unlettered stones rather than inscribed monuments. The walls of the Beginish oratory are 1.4 metres wide and built with thinner slabs on the inner face, a detail that reflects some care in construction. The external angles are slightly rounded, and a faint offset, a slight stepping or ledge, is still traceable on the northern outer wall. No clear entrance survives, though the rubble thins somewhat along the western side, hinting at where a doorway may once have been.