The Rahally hillfort in County Galway came to light only during archaeological investigations carried out ahead of the construction of the M6, and what emerged from that work was a monument of considerable scale that had gone largely unrecognised beneath the landscape of the Kilreekill ridge. Sitting on a spur with wide views to the north, west, and south-west, the site stretches roughly 450 metres in diameter and covers around 14.4 hectares, making it one of the larger hillforts known in Ireland. Yet for all its extent, the earthworks that defined it were surprisingly unimposing in cross-section, the fosses, or ditches, reaching only about 4 metres wide and 1.5 metres deep at their maximum.

The fort is multivallate, meaning it was enclosed by multiple concentric ditches rather than a single boundary, with four fosses arranged in rings around the hill. At the summit, the innermost ditch enclosed what later became a ringfort, a type of enclosed settlement more typical of the early medieval period, suggesting the site continued to attract occupation long after its original construction. The hillfort itself dates firmly to the Late Bronze Age, with radiocarbon dates from charcoal in the ditch fills spanning roughly 1090 to 520 BC. The finds recovered from those fills are quietly vivid: over 450 pottery sherds from at least seven flat-bottomed, bucket-shaped vessels, antler picks, chipped flint and chert tools, a polished stone axehead, a whetstone, and a fragment of bone pin. The animal bones concentrated in the inner and middle fosses point to cattle herding as the primary subsistence activity, supplemented by pig, sheep and goat, and the hunting of red deer. The complete absence of charred plant remains suggests that arable farming played little or no role here, an unusual detail that helps distinguish the economy of the site from many of its contemporaries. Entrances were identified as simple unstructured gaps in the fosses, aligned broadly east and west, with widths ranging from 1.4 to 6.2 metres, and no evidence of gates or wooden bridges. On the eastern side, rubble in the fosse fills points to a stone revetment reinforcing the earthworks, while a fragment of the original earth bank survived in the west only because a later field boundary happened to be built over it.