The one recorded near Miles in County Cork belongs to a category of monument so common that it has become almost invisible, yet so poorly understood that scholars still debate what these sites were actually for. A fulacht fia typically survives as a low, horseshoe-shaped mound of fire-cracked stone and dark, charcoal-rich soil, usually beside a stream or in a boggy hollow. The mound is the debris of repeated heating: stones were burned in a fire, then dropped into a water-filled trough to bring the liquid rapidly to the boil.

The majority of fulachtaí fia in Ireland date to the Bronze Age, roughly 1500 to 500 BC, though some have produced dates from the Neolithic and early medieval periods. For much of the twentieth century, the standard interpretation held that they were outdoor cooking sites, used to boil large joints of meat. More recent experimental archaeology has shown that the same technology works just as well for brewing, hide preparation, textile dyeing, and bathing, and the debate has not settled. What is consistent across the type is the method: the combination of a hearth, a wooden or stone trough, and a ready water source. The cracked and shattered stone, discarded after use because reheating fractured stone loses its efficiency, is what survives. At Miles, as at hundreds of comparable sites across Munster, that characteristic dark spread of burnt stone is what marks the spot.