Fulachtaí fia, the plural of fulacht fia, are among the most common prehistoric monuments in Ireland, low horseshoe-shaped mounds of fire-cracked stone left behind by repeated episodes of water-heating, most likely for cooking, though bathing and textile processing have also been proposed. Finding one is unremarkable. Finding six clustered together in Ballycummin is a different matter, and it raises questions about what this particular stretch of ground was being used for, and by how many people, over how long a period.

This site, recorded as fulacht fia 4 or Site F within the group, came to light not through a dedicated research project but through the kind of developer-led archaeology that has transformed our understanding of the Irish prehistoric landscape since the 1990s. Archaeological monitoring of a dual carriageway constructed as part of the Dell Factory Development in County Limerick brought the site to the attention of archaeologist Noel Dunne, who subsequently excavated it under licence 98E0433. What he found was a rectangular trough measuring 2.4 metres by 1.4 metres and between 0.35 and 0.4 metres deep, cut into the subsoil. Stake-holes around the edges showed that it had originally been lined with timber, forming a watertight basin into which heated stones would have been dropped to bring the water to temperature. Around the trough lay a burnt spread, the accumulation of discarded fire-cracked stone and charcoal that gives these monuments their characteristic mounded appearance, measuring 12 metres by 8.5 metres. The results were published in the excavations.ie summary for 1999.

The site sits within a wider designated monument grouping, recorded as LI013-229 through to LI013-234, and its location is documented in the excavation report compiled by Martin Fitzpatrick and uploaded to the record in July 2020. Because the discovery was made during road construction and subsequent development, the site is not accessible in the way that a field monument in open countryside might be. Visitors interested in the broader context of fulachtaí fia in Limerick would do better to consult the National Monuments Service database, where the full cluster is listed, than to expect anything visible on the ground at Ballycummin today.