It came to light in 1985, and even then it resisted full examination, its interior blocked by collapsed material that left archaeologists working only with what they could see from the entrance.

What they recorded is modest but telling. The chamber measures 1.9 metres in length and 1.45 metres in width, its roof formed from large flat stone lintels laid across the top. This is the classic construction of a souterrain, an underground stone-built passage or chamber found widely across early medieval Ireland, typically associated with nearby settlement and used for storage, refuge, or both. At the northern end, there appears to be a creepway, the narrow connecting passage through which a person would have had to crawl to move between chambers or to reach the surface, a feature common in more extensive souterrain systems. Whether a second chamber or a longer passage lies beyond the collapsed section at Roughgrove remains unclear. The site has not, as far as the available record shows, been fully excavated, and much of what lies beneath that fallen stone is still unknown.