A souterrain, one of the dry-stone underground passages or chambers that early medieval Irish communities built within or beside their ringforts, once opened here from a fosse, the defensive ditch running around the outer rampart of the fort. Then, at some point before 1934, the rampart was levelled, the souterrain was exposed, the stones were taken away, and the entrance was closed in. Nothing marks the spot today.

The detail comes from Bowman, writing in 1934, who recorded that the discovery happened when the outer rampart of the associated ringfort was being demolished. Souterrains are fairly common features of ringfort sites across Ireland, where they served various purposes, possibly as places of refuge, cool storage for foodstuffs, or concealed escape routes. What is less common is a written account of one being found and immediately erased. The entrance, Bowman noted, had opened from the fosse rather than from inside the enclosure itself, which is an unusual arrangement worth remarking on. Whether the passage extended inward beneath the fort, or simply ran along the edge of it, is now impossible to say. The stones were removed, the hole was closed, and the archaeology was effectively undone in the same moment it was noticed.