The feature in question is a souterrain, a type of man-made underground chamber or tunnel built from stone, typically associated with early medieval settlement and used for storage or as a place of refuge. That it survives at all is the more remarkable detail here, because the cashel surrounding it has fared rather less well.

The site is a cashel, which is the Irish term for a ringfort built from stone rather than earth and timber. At roughly 46 metres in diameter, it would once have been a considerable presence on this gentle east-facing slope. The defining wall, built in the drystone technique without mortar, is now largely collapsed, though its footprint remains legible: nearly three metres wide, with the rubble still standing about a metre and a half high on both the interior and exterior faces. McCaffrey noted the site in 1952, and it is likely early medieval in origin, the kind of enclosed farmstead that a prosperous family might have occupied somewhere between the sixth and twelfth centuries. A narrow boreen, the Irish word for a small rural lane, skirts the perimeter from the south-east around to the south-west, tracing a path that may itself reflect the long memory of the enclosure's presence in the landscape.

What makes the Tooreen cashel quietly compelling is precisely the combination of collapse and persistence. The wall is gone in any practical sense, and the site is described as poorly preserved, yet the souterrain at its centre endures, tucked into ground that has been grazed and weathered for over a thousand years. The boreen still follows the old curve.