The field name Lackmore translates loosely as "Large Grave", which is exactly what the Ordnance Survey cartographers recorded on their manuscript fair plan in the nineteenth century, and the name turned out to be accurate in ways they could not quite have anticipated.

When the Ordnance Survey Letters were compiled in 1839, whoever documented the site left behind a precise and rather vivid description: a monument roughly twelve feet long and four feet wide, bordered by a line of large standing stones acting as a kind of enclosure. Five of these stones were still visible at the time, three along the north side, one to the south, and one at the eastern end, all of them leaning noticeably inward. The account is consistent with the remains of a megalithic gallery, a type of prehistoric burial monument in which upright stones form the walls of an elongated chamber, sometimes covered originally by a long mound of earth or cairn. What makes Lackmore quietly melancholy is what came next. By the time mid-nineteenth-century antiquarians were writing up the monuments of the surrounding area, the site had already vanished from their accounts entirely. It seems the monument was destroyed in the short interval between that 1839 description and the publications of 1849 and 1851 that otherwise surveyed the same ground. Something that had survived thousands of years of Irish prehistory was gone within a decade of being formally noticed.