It looks modern. It carries no obvious drama. And yet it belongs to a series of eight cairns strung across inhospitable mountain terrain, their collective purpose being to mark a county boundary in a landscape where almost nothing else does.

A cairn, in the broadest sense, is simply a mound or heap of stones, and the practice of using them as markers stretches back thousands of years across Ireland and Britain. What makes this particular example quietly puzzling is the uncertainty that clings to it. When the Ordnance Survey mapped Ireland at six inches to the mile in 1837, this cairn was not recorded, which suggests it either did not exist at that point or was simply too minor to note. It was only picked up in the Sites and Monuments Record of 1989 and the Record of Monuments and Places in 1995, and even then it was classified cautiously as a possible cairn rather than a confirmed one. The same feature is recorded under a Leitrim reference number as well as its Sligo one, a small administrative wrinkle that reflects the boundary-straddling nature of the whole series. Whether the eight cairns were laid down as deliberate markers at some specific moment or accumulated more informally over time is not recorded.