It is not much to look at from the surface, but what that depression traces is the collapsed roof of a souterrain, an underground stone-lined passage built during the early medieval period, typically used for storage or as a place of refuge. These structures are found across Ireland in their hundreds, usually tucked within or beside ringforts, the circular enclosed farmsteads that once defined the rural landscape. What makes this one quietly interesting is the precision with which its shape has been recorded, even in ruin.

The hollow follows two arms meeting at a sharp angle. The longer arm, running roughly west-south-west to east-north-east at around 6.3 metres, turns abruptly northward and continues for approximately six metres along a north-north-west to south-south-east axis, giving the whole feature a total length of 12.3 metres and a width of around 2.9 metres. That deliberate change in direction is characteristic of souterrain design, where bends and constrictions were sometimes built in to slow unwanted intruders or to help regulate the internal atmosphere. The ringfort it belongs to sits alongside it as a companion monument, the two features together representing the remains of what was once a functioning early medieval farmstead, the underground passage serving the household above.