Large barrow on the top of Athgoe Hill, just about inside the county Dublin boundary. Athgoe Hill and Lyons Hill are the last, most north-westerly, of a series of hills/mountains that form an arc to the south of Dublin city.
Access to the barrow is easy as there's a track up to the aerial/mobile phone mast. It's quite henge-like, about 45 metres in diameter and also quite ploughed/eroded away. In fact the national monument's database has this as an enclosure, with the remains of the barrow downslope to the north of here.