It is a sweathouse, a type of early Irish sauna or steam bath, built entirely without mortar in the dry-stone tradition and shaped into a low beehive dome, and it once served as a primitive but effective therapeutic space where people would crawl inside after a fire had been lit and extinguished within, allowing the residual heat to induce sweating thought to ease rheumatism and other ailments. The entrance, facing south-east, measures just 0.7 metres in both height and width, meaning that entry would have required getting down on hands and knees, a posture that reinforces how intensely private and bodily the experience must have been.

The structure is circular, with an internal diameter of two metres and a surviving height of approximately 1.6 metres. When the scholar Richardson examined it in 1939, the corbelled roof was still largely intact, rising to two summits in a double-peaked arrangement unusual enough to merit specific comment. Corbelling is a construction technique in which successive layers of stone are laid so that each projects slightly inward over the one below, eventually meeting at the top without any keystone or mortar, a method used across early Irish architecture from passage tombs to monastic cells. Richardson also observed that the walls had been compactly packed with sandy clay and that the exterior showed what he described as a facade of semi-ashlar, meaning the stones had been worked or selected to present a relatively flat face. The roof has since collapsed. What is particularly striking about this site is its near-total absence from the cartographic record; it does not appear on the Ordnance Survey editions of either 1836 or 1876, which suggests it had already fallen out of use or recognition by the time systematic mapping of the Irish landscape was underway.