It measures roughly two and a half metres east to west and just over a metre north to south, rising to about three-quarters of a metre in height. To look at it, you might take it for any other piece of the landscape. The inscribed stone placed beside it tells a different story.

Mass-rocks are among the more quietly charged survivals of Irish history. During the Penal Laws, which restricted Catholic worship in Ireland through the late seventeenth and much of the eighteenth century, priests celebrated Mass outdoors and in secret, often in remote or sheltered spots chosen as much for concealment as for convenience. A natural rock outcrop at the edge of a hillside provided both a surface and a degree of cover. The Glanalin stone, set against the north face of an east-west running outcrop, fits this pattern exactly. The commemorative inscription beside it records that Mass was celebrated here again on the 17th of May 2000, a deliberate act of continuity linking the site's clandestine past to the present.

A series of white poles marks a path up from the nearby road, guiding visitors through the hillside terrain to the site. The setting, open pasture interspersed with gorse and exposed rock, gives some sense of what it would have meant to gather here in an earlier century, in a landscape that offered little shelter beyond what the rock itself provided.