The burial mound and standing stone once known locally as the Long Stone, in the townland of Grian in County Limerick, managed to appear in three different locations across successive editions of the Ordnance Survey maps, shifting first 35 metres to the west-southwest on a revised six-inch sheet, then 55 metres south of its original 1840 position on the 1897 twenty-five-inch edition. Whether this reflects genuine confusion on the ground, inconsistent survey methods, or the stone having been moved at some point, nobody has satisfactorily explained. The monument was never depicted on historic Ordnance Survey maps at all as a named feature in its own right, which only deepens the puzzle.

The Ordnance Survey's own field notes, recorded in the nineteenth century, described the Long Stone as a substantial pillar standing nearly upright, leaning slightly to the east, and reaching nine and a half feet in height, though surveyors noted that earth appeared to have been removed from its base, suggesting it may once have stood higher. At its widest the stone measured three feet across and roughly one foot ten inches in thickness. It stood at the centre of a layered earthen enclosure: an outer rampart of about sixty paces across, a shallow separating ditch, and then a central mound approximately eighteen paces in diameter, of roughly the same height as the outer bank. The hollow at the very centre of the mound, around the stone itself, was noted as sunken a few feet, a detail that surveyors found worth recording. The Ordnance Survey Name Book of the period mistakenly described the stone as a cromlech, a term properly used for a megalithic tomb with a capstone, and the error was corrected in later commentary. By 1916 or 1917, the antiquarian Thomas Johnson Westropp was still able to record the pillar standing in its fort in Grian, confirming it remained visible into the early twentieth century.

By the time the Archaeological Survey of Ireland examined the site in 2008, the picture had changed entirely. Surveyors recorded no visible surface remains, only a slight rise in the ground across the area. Evidence of small-scale quarrying activity was noted in the same field, which may partly account for the monument's disappearance. Aerial and satellite imagery from multiple sources, including Google Earth imagery dated June 2018, shows nothing distinguishable. The site sits on a gentle northeast-facing slope in what is now improved pasture, about 180 metres east of the townland boundary with Ardroe, and commands wide views in all directions. What a visitor encounters today is essentially a field with a barely perceptible undulation, and the knowledge that something once stood there that even the mapmakers could not quite pin down.