One of the lintels that once roofed an underground passage near Windgap has an ogham inscription carved into it, yet it was not placed there to be read. Ogham is an early medieval script, typically found on standing stones, in which letters are represented by notches and strokes cut along a central line. The stone here was reused as building material, its inscription already old and presumably unremarked when someone laid it across the passage roof. That detail, quiet as it is, opens a small window onto how earlier monuments were being casually dismantled and recycled, their meanings perhaps already lost, while new underground structures were being built.

The souterrain sits within a rath, a circular earthen enclosure of the kind used as a farmstead enclosure during the early medieval period in Ireland, and specifically in the north-western quadrant of that enclosure. Souterrains are dry-stone underground passages or chambers, generally associated with raths, and thought to have served as places of refuge or cool storage. This one is L-shaped: the entrance passage runs roughly east to west for about six metres before turning south for a further six metres, narrowing slightly as it goes. Two of its original roofing lintels remain in position in the southern arm of the passage. The structure is now roofless overall, open to the sky, which makes its stonework and layout easier to read visually but also means the atmosphere of enclosure that would once have defined the space is largely gone.

The displaced ogham lintel is catalogued separately from the souterrain itself, reflecting the fact that it belongs, in origin, to a different monument entirely. It is a reused stone, which means it had a first life elsewhere before being incorporated into this passage. Whether it came from a nearby standing stone, a burial context, or somewhere further afield is not recorded. What remains is the inscription, sitting in a structure that never had anything to do with the tradition that produced it.