It would be easy to walk past without a second thought, yet this shallow groove in the earth may be the collapsed remains of a souterrain, an underground stone-lined passage typically built during the early medieval period as a place of refuge, storage, or concealment.

The depression sits in the north-western sector of a ringfort, one of the circular enclosed settlements that were built across Ireland from roughly the fifth to the twelfth centuries, and which remain among the most common archaeological features in the Irish landscape. Here the feature runs from the ringfort's north-western bank to the northern corner of an associated house site, following the slight zigzag course that is characteristic of some souterrains, where a bent or angled layout served to restrict light, airflow, and uninvited entry. The site itself occupies the western end of a low east-west ridge, set among undulating rough pasture at Knockaville. The width of the depression, just over two metres, and its relatively modest depth suggest that whatever structure once existed below ground has long since given way, leaving only this faint surface trace to indicate what might lie beneath.