The 1907 OS six-inch sheet marks it in gothic lettering as "Cairnbaine Giant's Grave", and after that, cartographic silence. The name itself is a curiosity, combining a Gaelic element with the folkloric label that rural communities across Ireland attached to ancient tombs they could not otherwise explain.

What survives is most likely a dual court tomb, a type of megalithic monument common in Ulster and the northern half of Ireland, typically dating to the Neolithic period, roughly 4000 to 2500 BC. A court tomb generally consists of a roofless or partially roofed forecourt opening into one or more burial chambers, the whole structure enclosed within a long cairn of stone and earth. Here, the cairn is trapezoidal in plan, aligned roughly east-northeast to west-southwest, measuring 36 metres in length and up to 19 metres wide at its eastern end. That eastern end holds the better-preserved of the two tombs: a three-quarter court, partially enclosed rather than fully open, with two façade stones to the north of the gallery entrance. Two upright jamb stones topped by a lintel lead into a chamber roughly four metres long, with evidence of a continuing gallery beyond a pair of segmenting jambs. At the western end, a smaller chamber, about 2.3 metres long, opens to the west through double jambs. The structural description was recorded by de Valera in 1960, and the monument is classified as a National Monument in state guardianship.