On a broad plateau in Rath, County Waterford, there is a megalithic monument that no longer exists. What makes this particular absence notable is how precisely it was once recorded, and how completely it then vanished.

Around 1840, the antiquarian John O'Donovan documented the structure during fieldwork connected to the Ordnance Survey. He described it as a long, flat capstone resting on three upright stones, with a fourth broken upright to one side. This is a classic portal tomb form, sometimes called a cromlech, a term once widely used for any megalithic structure in which a large horizontal slab is raised above the ground on supporting stones. The monument was significant enough to be marked on the 1840 edition of the Ordnance Survey six-inch map, which gives some sense of how visible and intact it appeared to those producing what was then the most systematic cartographic survey of Ireland ever attempted. The Reverend Patrick Power, writing in 1906 on the place-names of the Decies, the old territorial name for much of County Waterford, appears to have noted the structure still standing, suggesting it survived more or less intact into the early twentieth century. At some point after that, it disappeared entirely, leaving no trace on the pasture land where it once stood.

What happened to it is unrecorded. Megalithic stones were frequently removed for use in field walls, gate posts, or building foundations during the nineteenth and early twentieth centuries, and a capstone of the size O'Donovan described would have been a practical resource to anyone working the land. The plateau setting, open and agricultural, would have offered little protection. The monument is now known only through a handful of written descriptions and a cartographic mark that outlasted the stones themselves.