The one at Kiltrassy in County Kilkenny is typical in its quiet anonymity, a low mound of fire-cracked stone sitting in the landscape without fanfare, easy to walk past without a second thought. The term fulacht fia, sometimes rendered as fulacht fiadh, refers to these prehistoric cooking sites, characterised by a horseshoe-shaped mound of heat-shattered stone surrounding a trough that would once have been filled with water. Stones were heated in a fire, then dropped into the trough to bring the water to a boil, a method that works surprisingly efficiently and has been demonstrated repeatedly in modern experiments.

Most fulachta fia in Ireland date to the Bronze Age, broadly speaking the period from around 2500 to 500 BC, though some sites show evidence of use into the early medieval period. They tend to appear near water sources, streams or boggy ground, which made filling and refilling the trough practical. The mounds themselves are the accumulated debris of repeated use, stones that had cracked and splintered beyond further use were simply tossed aside, building up over time into the characteristic low crescents that survive today. The Kiltrassy site sits within a county that has a notable concentration of such monuments, reflecting both the density of Bronze Age settlement across the Kilkenny landscape and the preserving qualities of the soil and pasture that has kept so many of these low earthworks from being ploughed away entirely.