There is no depression in the ground, no telltale hollow, no surface feature of any kind to suggest that just beneath your feet sits a carefully constructed souterrain, an ancient underground passage or chamber system typically built during the early medieval period for storage, refuge, or concealment. The absence of any visible trace is, in its own way, the most striking thing about it.

The structure was investigated in 1932 by the National Museum of Ireland, and what was found beneath the hillside were two earth-cut chambers arranged at right angles to each other, a configuration that is relatively unusual. The first chamber, which served as the original entrance, measures roughly 2.52 metres in length and 1.5 metres in width. The second is slightly longer at 2.74 metres, though a little narrower at 1.3 metres. Extending from the southern end of that second chamber is a drain covered with flagstones, a practical detail that speaks to the care taken in the original construction. The souterrain sits approximately ten metres south of a cashel, a type of stone-walled circular enclosure used as a farmstead or small fortified settlement in early medieval Ireland, and the two features were almost certainly part of the same domestic landscape. McCarthy noted the site in 1977, and it has been known to archaeology since the 1930s, even if the ground above it gives nothing away.