Marked on Ordnance Survey maps of both 1839 and 1940, first in gothic lettering as a "Giant's Grave" and later as a "Dolmen", the structure was already a known curiosity long before any cartographer fixed it to paper. A dolmen is a megalithic tomb, typically consisting of large upright stones capped by a horizontal slab, and this one reportedly stretched some 23 feet, roughly seven metres, along the bottom of a gentle south and east-facing slope near the shoreline.

The earliest written account comes from the Dublin Magazine of August 1764, which recorded that length and little else. Sixteen years later, in 1780, the artist Gabriel Beranger made a sketch of the structure, a drawing that has never been published and exists somewhere unprinted in the record. The monument was well-documented, then, by the standards of its time. But by 1975, when archaeologists opened a trench measuring twenty metres by five metres across the site as part of excavation E000142, they found nothing at all. No stone, no foundation, no trace of any megalithic structure. The conclusion reached by Cahill and Lynch, who reported on the work, was straightforward: erosion by the sea had removed every physical remnant. The monument had not been dismantled or robbed out; it had simply been swallowed.

What remains is a place defined by absence. Carnsore Point is a low, exposed headland, the kind of coastal edge where the sea does not so much arrive as insist, and the fate of this particular monument is a quiet illustration of how much has been lost not to human interference but to geography and time. The maps still name it. The 1764 account still describes it. Beranger's unpublished sketch still, presumably, exists. The grave itself does not.