It is, in fact, the remains of a fulacht fia, a type of prehistoric cooking or industrial site found in great numbers across Ireland, typically dating to the Bronze Age. The characteristic spread of burnt and shattered stone beneath the surface is the giveaway; fulachtaí fia were built around a water trough, usually timber-lined, into which fire-heated stones were dropped to boil water. Over time, the cracked and discarded stones accumulated into the horseshoe-shaped mounds that survive today, often in low-lying or waterlogged areas just like this one.

What makes the Charlesfield site quietly notable is that it does not sit alone. A second fulacht fia lies immediately to the north-east, the two sites close enough together to suggest this stretch of marshy ground was visited and used repeatedly, perhaps across generations. The wet, boggy terrain would have made practical sense; a reliable water source was essential to the whole process, and low-lying ground held water well. The proximity of two such sites raises questions that are easier to ask than to answer: were they used at the same time, by the same community, or do they represent separate episodes of activity separated by years or centuries? The archaeology, at least as it survives above ground, does not say.