The term, roughly translating as "cooking place of the deer" in Irish, refers to the remains of ancient outdoor cooking sites, typically identified today as a low horseshoe-shaped mound of burnt and shattered stone beside a filled-in trough. One such site sits at Milltown in County Kilkenny, largely unannounced and easy to pass without a second glance.

The mechanics of a fulacht fia were straightforward but effective. A trough was dug into the ground, often close to a natural water source, and lined to hold water. Stones were heated in a fire and then dropped into the trough, raising the water temperature enough to cook meat or, as some researchers have proposed, to brew ale or process hides. The broken, heat-shattered stones were piled to the side after each use, and it is these accumulations of fire-cracked material that survive as the characteristic mounds visible today. The majority of fulachta fia in Ireland date to the Bronze Age, broadly spanning from around 2000 BC to 500 BC, though some sites show evidence of use across multiple periods. County Kilkenny has a notable concentration of them, and the Milltown example adds to a pattern that suggests this stretch of the Irish midlands and south-east was well settled and actively used throughout prehistory.

Beyond its location near Milltown, the specific details of this particular site remain limited in what is publicly available at present, and little can be said with confidence about its dimensions, condition, or immediate surroundings. What can be said is that its existence is a reminder of how ordinary and widespread these features once were, built not by elites or for ceremony, but by people going about the practical work of feeding themselves in a landscape that was, even then, already long inhabited.