Wedge tombs are the most numerous of Ireland's megalithic monument classes, generally dating to the late Neolithic and early Bronze Age, and they take their name from their characteristic tapering plan, wider and taller at the entrance end than at the rear. The Baurnadomeeny example, however, is not a simple stone box in a field. It is an elaborately layered structure, concentric rings of stone working inward toward a central gallery, the whole thing cairned over and kerbed with inward-sloping slabs to a diameter of fifteen to sixteen metres.

When O'Kelly excavated the site in 1959, what emerged was a monument of considerable internal organisation. A septal-stone, a single upright slab set across the interior to create a division, separates the gallery into a short portico and a longer main chamber. The portico narrows slightly from front to back, from 2.4 metres wide at the entrance to 2.1 metres at the septal-stone, and two pillar-like stones running along the main axis support the largest of three roof-slabs. A small cist, a stone-lined box roughly a metre square, is built against the southern side of the portico. The main chamber, 4.3 metres long and covered by four substantial roofstones, lacks a backstone entirely. Between the outer kerb and the gallery itself, an incomplete circle of stones about eleven metres across encloses irregular arcs of large uprights, the remnants of an elaborate structural system that once enclosed the sides of the gallery. Buttress-stones were found outside both lines of outer walling. What the excavation also revealed was twenty-one cremated individuals: five in the portico, one in the main chamber, twelve to the south of the tomb, and three just outside the kerb at the south-west. Among the few objects recovered were worked flint and chert pieces, including a plano-convex flint knife, the shaped, flat-based form typical of the period, and pottery sherds associated with one of the burials. Perhaps the most quietly arresting detail is on the inner face of one of the northern side-stones in the portico: incised lines, thought to be of ancient origin, scored into the stone by someone who stood inside this structure a very long time ago.