A burnt mound, in archaeological terms, is the accumulated debris of repeated heating, typically a midden of fire-cracked stones dumped beside a trough or pit where water was boiled using hot rocks. They are found across Ireland in considerable numbers, generally dating to the Bronze Age, and they tend to turn up in low-lying, waterlogged ground. Their precise function is still debated, with cooking, bathing, and industrial processing all proposed as possibilities. What makes the Ballymun example quietly interesting is the context of its discovery: not a rural field or a bog margin, but one of Dublin's most intensively developed urban fringes.

The site came to light not through any planned investigation of the past, but through the planning machinery of the present. A geophysical survey carried out under Licence 08R117, followed by a test excavation under Licence 09E0479, were undertaken as part of the proposed Metro North development, the long-running project to extend rapid transit northward from the city centre. The excavation, reported by Hession in 2009, uncovered an oval-shaped deposit measuring roughly five metres east to west and seven and a half metres north to south. The deposit consisted of dark, almost black sandy silt packed with heat-shattered burnt stones, the classic signature of a fulacht fiadh, as these monuments are sometimes called in older literature. To the west of the main spread, investigators found what appeared to be a ditch or field boundary around 1.85 metres wide, while one metre to the east a narrow slot-trench, just 0.2 metres across, was filled with black silty clay heavily stained with charcoal.

There is nothing to see at the surface today. The monument exists in the archaeological record rather than the landscape, documented through the licensing system and noted in the national Sites and Monuments Record. For anyone interested in the deep prehistory threading beneath Dublin's northern suburbs, the significance lies in that contrast: a deposit laid down in a marshy Bronze Age landscape, uncovered briefly by machinery intended to speed commuters from one end of the city to the other, then recorded, noted, and subsumed again beneath the ongoing work of the modern city.