The souterrain at Cooleenaree in County Cork is a little different. When a researcher named Broker examined it in 1937, what he found was a tunnel carved entirely from compacted earth, no stonework at all, held in place simply because the soil was solid enough to hold its own shape. That distinction, modest as it sounds, makes it a slightly unusual example of a feature found at hundreds of sites across the country.

A souterrain is an underground chamber or passage, typically associated with ringforts, the circular enclosed settlements that dot the Irish countryside in their thousands and date broadly to the early medieval period. They were used for storage, refuge, or both, and they were often deliberately designed to be difficult to navigate quickly. The Cooleenaree example follows that logic: Broker recorded a passage roughly four and a half feet high and four feet wide, which turns twice along its course, the kind of layout that would slow down anyone forcing their way through in a hurry. It sits in the south-western quadrant of the ringfort beside it, and today its presence is marked by a depression in the ground, around two metres wide and just over a metre deep, a quiet surface echo of what lies below.