The entrance was noted in 1931, but no one apparently went further in, and today there is no visible trace of it at the surface at all.

A souterrain is an underground stone-lined passage or chamber, typically constructed during the early medieval period in Ireland and used variously for storage, refuge, or concealment. What makes the Killeenleagh example quietly unusual is the detail that it is cut directly into rock rather than built up from dry-laid stone, and that when Nyhan recorded it in 1931, the chambers beyond the entrance had not been examined. That single line of observation has remained the entirety of what is known. No subsequent exploration appears to have been documented, and the site leaves no impression on the landscape above it.