This one came about because a piece of earthwork was being flattened. When levelling work began on a trivallate ringfort at Bengour in County Cork in 1979, machinery uncovered something that had been sealed underground for centuries: a souterrain, the kind of low, stone-lined or earth-cut underground passage and chamber that early medieval communities in Ireland used for storage, refuge, or both. There is nothing to see at the surface today, no mound, no dip in the ground, no marker. The structure exists entirely beneath the field.

Hurley and Hurley, writing in 1979, recorded what had been exposed: two earth-cut chambers connected by a creepway, the narrow crawl-through passage that links chambers in this type of structure, deliberately tight to slow down any unwanted visitor. The first chamber measured roughly 2.5 metres long, 1.6 metres wide, and about a metre high; the second was slightly smaller at 2 metres by 1.5 metres, with a ceiling height of around 1.1 metres. Neither would have allowed a person to stand upright. The original entrance is thought to have been at the eastern end of the first chamber, though the levelling that revealed the site also disturbed it, and no entrance survives in any usable form. The ringfort it belonged to was trivallate, meaning it had three concentric enclosing banks or ditches, a form associated with higher-status settlements in early medieval Ireland. That a souterrain was tucked beneath such an enclosure is not unusual; the two features frequently occur together, the underground space functioning as an annex to the defended settlement above.