The term refers to a type of monument found in extraordinary numbers across Ireland, typically consisting of a horseshoe-shaped mound of fire-cracked stones beside a trough, usually timber-lined and dug into wet ground. The method worked by heating stones in a fire and dropping them into water in the trough until it boiled, allowing large cuts of meat to be cooked efficiently. Ireland has more of these sites than almost anywhere else in Europe, with estimates running to several thousand recorded examples, yet individual sites rarely attract much attention.

Fulachtaí fia, the plural form, cluster most densely in Munster, but Mayo has its share, often sited near boggy ground or stream margins where water was reliably close to the surface. The fire-cracked stones that form the characteristic mound are essentially the waste material of repeated cooking events, discarded as they became too fractured to hold heat effectively. Most date to the Bronze Age, broadly between 1500 and 500 BC, though some sites show evidence of use across longer periods. The Cashel example sits within a county whose boglands have preserved organic material and prehistoric features with unusual fidelity, meaning that even a modest mound can carry a considerable depth of time within it.