It measures roughly fourteen metres long and twelve metres wide, and it has been sitting quietly in that field for somewhere between three and four thousand years. It is a fulacht fia, one of the most common prehistoric monument types in Ireland, and yet one of the least understood.

A fulacht fia is essentially the debris left behind by an ancient cooking or heating site. The typical arrangement involves a trough dug into the ground near a water source, into which stones were heated in a nearby fire and then dropped to bring the water to the boil. Over time, the repeated heating and cooling caused the stones to crack and shatter, rendering them useless. These broken, fire-reddened fragments were cleared away from the working area and piled to one side, creating the distinctive horseshoe-shaped or oval mounds that survive across the Irish countryside in their thousands. The dark soil associated with them comes from the charcoal and organic residue of centuries of burning. The siting beside a stream at Carrigagour fits this pattern precisely, since reliable access to water was essential to however the site was used. What exactly these sites were for remains debated: cooking meat is the long-standing theory, but proposals ranging from textile processing to communal bathing have all attracted serious scholarly attention in recent decades.