A souterrain is an underground stone-lined passage or chamber, typically constructed during the early medieval period in Ireland, used variously for storage, refuge, or concealment. This one leaves no trace at ground level, which places it in a quietly unsettling category of archaeological sites: known to exist, recorded in the literature, but presenting nothing whatever to the eye.

The site came to light not through organised excavation or aerial survey but because the landowner noticed something. The discovery is referenced in a 1965 publication by Rynne, suggesting the find was made around that time, likely during agricultural work on land that had already been altered by the process of reclamation. That reclamation, the draining and levelling of boggy or rough ground to make it suitable for pasture, is probably the reason the souterrain no longer announces itself above the surface. The land has been worked over, the topography smoothed, and whatever slight depression or collapse might once have signalled an underground structure has long since been absorbed into the field.