A fulacht fia is, in essence, a burnt mound site: a place where people repeatedly heated stones in fire, dropped them into water-filled troughs to bring the liquid to a boil, and left behind great spreads of cracked, heat-shattered rock and dark silt. Thousands of these sites survive across Ireland, yet what exactly they were used for, cooking, bathing, textile processing, or some combination, remains genuinely contested among archaeologists.

The Kellymount site was excavated in 2007 and 2008, ahead of the N9/N10 Kilcullen to Waterford road improvement scheme. What emerged was a more complex arrangement than many comparable sites. Thirteen burnt spreads, the characteristic signature of repeated high-temperature activity, overlay three troughs cut into the ground, two of which were conjoined, sharing a wall. To the north of these sat a sub-circular stone platform, built from fourteen slab-like stones laid over a bed of pebbles, a feature whose function is not entirely clear but which may have served as a working surface or structural support. Three stake-holes to the east of one trough suggest some kind of timber framework once stood nearby, perhaps a shelter or a rack. Several pits to the east and south-east of the troughs may have been used for storage or roasting, and three linear cuts are interpreted as drainage gullies, managing the flow of water around the working area. Together, these elements point to a site that was used repeatedly and with some degree of organisation, rather than casually or briefly. The excavation was carried out under licence E3858 and the findings were reported by Wiersbicki in 2009 and 2010.