The site at Castleroan, on the border between County Offaly and Tipperary North, came to light not through a targeted heritage survey but through the routine trial-trenching that precedes major road schemes, which has become one of the more productive, if unglamorous, ways of discovering prehistoric Ireland.

Phase 2 excavations, directed by John Tierney of Eachtra Archaeological Projects under licence E3909, were commissioned by Laois County Council and the National Roads Authority as part of Contract 1 of the 35km scheme. The site, designated Castleroan 1 Area 7.2, had first been flagged during testing in 2007. Full excavation across a 60 by 30 metre area revealed an extraordinary density of features: five slot-trenches, two hearths, 60 post-holes, 55 pits, and 68 stake-holes. Most of these were concentrated within a roughly 20 by 20 metre zone, and together they represent the footprints of at least two separate structures. Structure A, in the north-western part of the site, was the more legible of the two. It had a double ring of timber posts, an inner ring of around 5 metres in diameter and an outer ring of about 7 metres, with a hearth and several pits in the interior. Such a concentric post arrangement is a known form for later Neolithic or Early Bronze Age roundhouses, where the inner ring of uprights supported the roof and the outer ring helped brace the walls. Structure B lay just 5 metres to the south. Its plan was less complete, but two slot-trenches, which are narrow foundation trenches dug to receive a continuous timber wall plate or sill beam, appear to mark an entrance roughly 1.4 metres wide, with a hearth inside whose base had been cut by four smaller stake-holes, likely the remnants of a simple frame or support built around the fire itself. The finds tie the occupation to the Beaker period, a horizon running roughly from 2500 to 1800 BC, characterised across Europe by a distinctive style of decorated pottery used in domestic and funerary contexts. The sherds recovered here, alongside a rubbing stone and worked pieces of chert and flint, suggest ordinary household activity rather than anything ceremonial.