The structure known as the Eastern House sits within a conjoined enclosure on that hill, and when archaeologists cleared earth from beneath one section of its circular boundary wall, they found a substantial bed of ash running for some eight metres along the interior, underneath the very foundations. Macalister and Praeger, who excavated the site in 1928, concluded that "some kind of foundation rite seems to be indicated." It is the kind of detail that makes a site quietly difficult to forget.

The Eastern House was, in Macalister and Praeger's judgement, the most important structure remaining within its enclosure. It is roughly circular, about 13.4 metres in diameter, with walls of earth approximately three metres thick at the base, faced with dry-stone masonry. The entrance passage, paved with flat irregular slabs and oriented to face east, narrows as it moves inward, and two post-holes for door-posts survive at its outer end. Inside, the space is divided into compartments and chambers, with a three-chamber annexe attached on the southern side. A step inserted into the entrance passage at some point after the original paving was laid suggests the building was modified during its use. The 1837 Ordnance Survey six-inch map records the site as a large circular ringfort with a D-shaped annexe, and also marks a souterrain, an underground stone-lined passage, at its centre, along with what appear to be the earthen footprints of at least two hut sites within the enclosure. The site sits within a dense cluster of monuments: a mound barrow lies 200 metres to the north, an embanked roadway described on old maps as an "ancient road" runs up to its southern side, and a ritual pond known as Loch Lugh lies just 170 metres to the northwest. The results of the 1928 excavation were re-examined by Rónán Schot in 2006, whose reinterpretation has added further layers to the understanding of what this complex of structures may have represented on a hill already laden with mythological and political significance in early medieval Ireland.