The stone itself is not a grave at all, as far as anyone knows, but a single upright pillar of irregular shape, nearly two metres tall and roughly a metre across, planted on the highest point of a low drumlin ridge. Drumlins, the smooth elongated hills that give so much of Cavan and Monaghan their particular rolling texture, were formed by glacial activity during the last Ice Age, and whoever raised this stone chose the most prominent local high point with some care.

The monument was catalogued by Ruaidhri de Valera and Seán Ó Nualláin in their 1972 survey of prehistoric standing stones, which remains a foundational reference for this class of monument across Ireland. Standing stones as a category are notoriously difficult to date or interpret with confidence. They were erected across a long span of prehistory, and their purposes seem to have varied, ranging from boundary markers to ritual focal points to memorials. What the Cornabaste stone meant to those who raised it is unknown. What is clear is that its position on the drumlin crest would have made it visible across a wide sweep of the surrounding landscape, and that its bulk, at 1.9 metres high with a cross-section of 1.1 by 1 metre, represents a considerable feat of placing and raising.