What makes it quietly peculiar is not the cairn itself but what sits on top of it: three small conical cairns, built directly onto the main structure, giving the whole arrangement a layered, almost ceremonial appearance that goes well beyond a simple pile of field-cleared rock.

This cairn is one of a series of eight that together trace the boundary between counties Sligo and Leitrim across what the record describes plainly as inhospitable mountainous terrain. The main mound is subcircular in plan, measuring roughly 9.3 metres north to south and 7.7 metres east to west, and rising to a maximum height of just half a metre, so it sits low against the plateau rather than announcing itself dramatically. Boundary cairns of this kind, used as physical markers along administrative or territorial edges, were a practical solution to the problem of fixing lines across landscape where hedges would not grow and walls were impractical. Interestingly, this cairn does not appear on the 1837 edition of the Ordnance Survey six-inch map, which raises questions about whether it was simply overlooked by early surveyors or whether its formal recognition as a county boundary marker came later. The site is also recorded under a Leitrim reference, reflecting the fact that the boundary runs directly through or beside it, making it simultaneously a Sligo and a Leitrim monument.

Truskmore is the highest point in the Dartry Mountains, and the plateau around it is exposed and trackless in the way that high bog ground tends to be. The cairn sits at the eastern apex of that plateau, which gives it a long view south-eastward but also means the approach from any direction involves rough, wet ground. There are no formal paths to this site, and the terrain is genuinely difficult in poor weather.