Yet that is precisely what turned up at Farrankelly, where a circular smelting furnace, packed with charcoal and metalworking slag, had been quietly waiting beneath the topsoil for an unknown stretch of centuries.

The story of its discovery began not with a spade but with patterns visible from above. In 2015, archaeologist Joanna Leigh carried out a geophysical survey of the area earmarked for residential development by Cairn Homes, using a gradiometer, an instrument that detects subtle variations in the magnetic properties of soil, often caused by ancient pits, ditches, or burning. The survey picked up two clear circular ditch-like features, roughly 11.25 metres and 12.25 metres in diameter, with crop marks on the surface suggesting their presence. Both appeared to sit within a larger, less distinct circular feature, possibly an enclosure of some kind. Testing followed in 2017, led by Rob Lynch and Enda Lydon of IAC Archaeology, and identified three separate areas of archaeological interest across the site. It was Area 3A, in the southwest corner, that proved the most revealing. When Muireann Ní Cheallacháin excavated the furnace there in 2020, she found a feature circular in plan with four distinct fills. The layering told a particular story: a non-oxidised deposit sealed the base of the feature, indicating that the furnace had been used, allowed to cool and partially fill, and then put back into use as a smelting furnace on at least one further occasion. Around its upper fills ran a ring of burnt clay just 0.1 metres wide, the scorched signature of the heat that had once radiated outward from its core. The main fill was thick with charcoal fragments and slag, the glassy, dense waste product left behind when metal is smelted from ore, with lesser quantities of the same material found higher up.