Fulachtaí fia, as they are collectively known, are among the most common prehistoric monuments in Ireland, typically appearing as low, horseshoe-shaped mounds of fire-cracked stone beside a water source. The standard interpretation is that stones were heated in a fire and then dropped into a water-filled trough to bring it to the boil, whether for cooking, bathing, or some industrial process such as working leather. What makes the Sallymount example quietly interesting is how unremarkable it looks on paper, and how completely it escaped the notice of the Ordnance Survey mapmakers who recorded the landscape in earlier centuries.

The site was never marked on historic mapping and might have remained unknown had it not been for road construction. In 2006, archaeologist Tracy Collins identified it during test trenching carried out under Ministerial Direction Order A026/104 ahead of work on the Southern Limerick Ring-Road. Aidan Harte subsequently excavated it as part of what the project recorded as Gortnalahagh Site 2. The remains measured roughly six metres by five metres and were only around ten centimetres deep, consisting of a spread of burnt material covering a single trough, within which four stakeholes had been cut. A second burnt spread lay approximately 2.75 metres away, covering an irregularly shaped pit, suggesting the site saw more than one episode of use or perhaps two distinct activity areas. Radiocarbon dating confirmed the site belongs to the Early Bronze Age, placing it somewhere in the broad span between roughly 2200 and 1500 BC, when fulachtaí fia were at their most widespread across Ireland.

The site lies in gently rolling pasture approximately 1.5 kilometres south-east of the River Shannon, in the kind of low-lying ground that Bronze Age communities consistently favoured for this type of activity, presumably because groundwater or a nearby stream made it practical. Given that it was excavated as part of a road scheme, the physical remains are unlikely to be visible above ground today. What the site offers now is less a place to stand and observe than a point on the map that prompts reflection on what road-building archaeology has quietly recovered from fields that had shown no surface trace of occupation for thousands of years.