What remains of this wedge tomb, a type of megalithic burial monument built during the late Neolithic and early Bronze Age, is a partially dismembered stone passage that once served as a communal grave. Wedge tombs are so called because the burial gallery is typically wider and taller at the western end, tapering toward the east, and the structure at Ballynoony follows that pattern precisely, its walls dropping in height as they run from west to east.

The gallery measures just over five metres in length, running from roughly one metre in width down to about seventy centimetres at its narrower end. Four orthostats, the upright stones forming the structural walls, survive on the northern side, including one set transversely near the western end. Only two remain on the southern flank, with a pair of buttress stones set just outside them. Beyond these inner walls, four outer-wall stones still stand to the north, one of them nearly fallen flat. The space between the outer wall and the gallery is packed with rubble, among which a further buttress stone can be identified toward the western end. Two large displaced slabs lie just west of the gallery entrance. There is faint evidence of an original earthen mound to the north and south of the structure, though what little survives is obscured by field debris and material thrown out during earlier excavations. The removal of the roofstones is documented in sources from 1851 and 1897, confirming the damage was already done well before any formal archaeological interest in the site. The tomb sits close to the summit at 192 metres, looking out over the Black Water valley to the south-west, a position that would have made it conspicuous in the landscape for thousands of years before anyone thought to quarry its covering stones.