What makes this one at Knockdoorah quietly arresting is the layering of what may lie within and beneath it. The circular enclosure, about 34 metres across, carries the visible marks of early medieval domestic life, a causeway entrance to the east, an external fosse, earthen banks of varying heights around the perimeter. But in its north-west quadrant there is a possible children's burial ground, and in the south-east a large fallen stone beside a depression in the ground that may indicate a souterrain, an underground stone-lined passage or chamber that early Irish farmers used for cold storage or, in times of trouble, concealment. The site looks south-east toward The Paps of Dana, the twin-peaked mountains in the Derrynasaggart range that take their name from the goddess Danu and have been a landmark in this part of Kerry for as long as people have lived here.

The rath was recorded in the 1940s in the Schools Manuscript, a nationwide folklore collection gathered largely through Irish schoolchildren, which noted it as the "black-fort" on land belonging to a Thomas Daly. That informal name carries its own interest. Black-fort designations in Irish folk memory often attached to enclosures that retained an atmosphere of unease or otherworldly association, places set apart from everyday use. The physical structure itself is typical of a rath, a term used for the earthen ringforts built across Ireland roughly between the fifth and twelfth centuries as farmsteads for individual family groups. What survives at Knockdoorah is overgrown and eroded, the inner bank standing less than a metre high on the interior face, the outer bank rising to around 2.2 metres where best preserved. Field boundaries have been built up against the perimeter on the north and north-north-east, and they skirt the edge to the south, suggesting the enclosure has shaped how this land has been divided for a long time.