The conditional phrasing matters here. A mound roughly two metres by one and a half metres sits in the western half of the fort's interior, partly made up of field clearance stones, and it is under or within this feature that the underground structure supposedly lies. Whether the souterrain still exists in any meaningful form, or whether it collapsed and was gradually absorbed into the landscape long before anyone thought to look closely, remains an open question.

The earliest written notice comes from Bowman in 1934, who noted the mound and recorded the local tradition that a souterrain had once been there. That phrase, "it is said", does quiet but considerable work. It suggests the knowledge had already passed from direct observation into oral memory by the time Bowman encountered it, meaning the structure was likely inaccessible, obscured, or already gone. Souterrains are found across Ireland in association with ringforts, the circular enclosed settlements that were the dominant form of rural habitation from roughly the early centuries AD through the early medieval period. They were built without mortar, relying on carefully placed stone to hold their shape, which made them vulnerable over centuries to collapse, robbing for building material, and gradual infill. The mound at Gneeves, partially composed of clearance stones, may represent exactly that kind of slow burial.