This ancient standing stone, measuring just over a metre high and nearly 1.3 metres wide, has been incorporated into the modern landscape in an unusual way; it now forms part of the trigonometrical station at the mountain's peak. Only its northern face remains visible, the rest obscured by the survey marker that was built around it.

The stone itself is relatively modest in size compared to some of Ireland's more famous megalithic monuments, with a thickness of about 30 centimetres and oriented along an east-west axis. What makes it particularly intriguing is how it represents the layering of history on this windswept mountaintop. The original purpose of the stone, likely erected during the Bronze Age, remains a mystery; it could have served as a territorial marker, a memorial, or held ritual significance for the people who placed it there thousands of years ago.

Today, this ancient marker shares its space with the triangulation point used by the Ordnance Survey to map Ireland's landscape. It's a fitting combination really; both the standing stone and the trig point serve as fixed points in the landscape, one ancient and one modern, each marking human attempts to understand and define the land around them. The stone's location in Listicall Upper offers commanding views across the Donegal countryside, making it clear why this spot has attracted human attention across the millennia.