At Thomondtown in County Dublin, exactly this kind of site came to light not through deliberate excavation but through the routine monitoring that accompanied road construction, a reminder of how much archaeology surfaces only when the ground is opened for other reasons entirely.

The site was identified in 2001 during works on the Airport-Balbriggan bypass, and it follows the classic pattern of a fulacht fiadh, a term used for burnt mound sites found widely across Ireland and Britain. The general interpretation is that stones were heated in a fire, then dropped into a water-filled trough, bringing the water rapidly to the boil. What this process was actually used for remains debated: cooking is the most common suggestion, but brewing, hide-working, and bathing have all been proposed by researchers. At Thomondtown, there were two troughs and a single hearth, all of them filled with the cracked and blackened stones that are the defining signature of these sites. The details were recorded by Lynch in 2004 and the site was subsequently compiled by Geraldine Stout as part of an ongoing effort to document such monuments across the country.

Because the site was uncovered during infrastructure development rather than as part of a planned heritage project, there is nothing to see at ground level today. The bypass itself is the only visible trace of the disturbance. That said, the broader Thomondtown area north of Dublin sits in a landscape with a long human presence, and anyone with an interest in the archaeology of road corridors might find it worth reading Lynch's 2004 report, which places this site in a wider regional context. Fulachtaí fia are often found near water sources, so the local topography, wherever low or marshy ground survives nearby, can still offer a sense of why this particular spot was chosen several thousand years ago.