A souterrain, which is a dry-stone underground chamber or tunnel typically associated with early medieval Irish settlements and used for storage or refuge, was first uncovered here in 1875 when a road was cut through the northern side of the ringfort. It was destroyed in the process, or so local tradition and early twentieth-century commentators assumed. Then, around 1976, construction of a yard within the same ringfort turned up a second stone-lined chamber, roofed with large slabs, on the south side of the road. Rather than excavate it, whoever found it simply left it in place and covered it over again.

The paper trail is thin but telling. Bowman, writing in 1934, and Broker, writing in 1937, both documented the 1875 road-cutting episode and noted the souterrain's apparent destruction. What neither could have known was that a separate opening, on the north side of the road along the inner bank of the ringfort, still survives above ground. This visible chamber measures roughly two metres in length, no more than one metre across at its widest, and only about forty centimetres high at the entrance, though it becomes both higher and wider as it extends inward. Archaeologists have suggested that the destroyed passage, the covered chamber to the south, and this accessible northern section may all be parts of a single large souterrain running beneath the ringfort, its full extent still unknown.