That three pillars within a single souterrain should bear ogham inscriptions is unusual enough to pause over. Souterrains, stone-lined or earth-cut underground passages associated with early medieval settlements in Ireland, were typically used for storage or refuge, not as sites of inscription.

The souterrain was discovered in 1905 in the north-western quadrant of a ringfort. Ringforts, the enclosed farmsteads of early medieval Ireland, often concealed souterrains within their interiors, and this one proved more complex than most. McCarthy, writing in 1977, recorded four subrectangular chambers extending to the east of the stone-built first chamber. That first chamber is roofed with six capstones supported by the chamber sides and seven pillars, three of which carry the ogham carvings. The remaining chambers are earth-cut with barrel-vaulted ceilings, a technique in which the ceiling curves upward in a continuous arc without any supporting stonework. The chambers are tightly proportioned throughout; none exceeds a metre in height, and widths range between roughly 1.3 and 1.7 metres. The longest single chamber runs to 3.8 metres. Crowley noted the site in 1906, and Macalister, whose cataloguing of ogham stones across Ireland remains a foundational reference, included it in his 1945 corpus. Today, a collapsed area in the north-western section of the fort above ground marks where the underground structure lies beneath.