They are all that remains visible of a souterrain, an underground passage or chamber built into the earth, typically during the early medieval period and associated with the cashels and ringforts of early Irish settlement. The rest of it is blocked up, its interior inaccessible, but those three exposed roof lintels trace the line of the original structure running roughly north-north-west to south-south-east.

The souterrain sits within a cashel, a type of stone-walled enclosure that served as a farmstead or defended settlement in early medieval Ireland. The parent cashel at this site is a recorded monument in its own right. Souterrains of this kind were commonly used for food storage, as refuges, or as places to shelter livestock and valuables during times of threat. Finding one within the north-west quadrant of its enclosing cashel is consistent with how such features were often positioned, tucked against or near the interior wall and away from the main living area. That this one survives at all, even in blocked and partial form, is largely down to the durability of the stone lintels that once formed its roof.