That act of erasure is now, in a quiet way, the most notable thing about the site.

A souterrain is a man-made underground structure, typically stone-lined, associated with early medieval settlement in Ireland. They were used variously for storage, refuge, or as annexes to dwelling areas, and are often found within or close to a rath, the circular earthwork enclosure that formed the basis of a farmstead during the early medieval period. At Crannagh, a possible rath has been identified in the same field, and within its interior there was reportedly both a mound and the L-shaped souterrain. The account comes from the landlord himself, who described these features before confirming that he had filled the souterrain in. No visible surface trace now survives of either the passage or, apparently, any meaningful remnant of the mound. What the souterrain contained, how it was constructed, or how far it extended beneath the ground, remains entirely unknown.