When archaeologists were called in to monitor the laying of service pipes and cables, they uncovered something remarkable beneath the soil: a series of ancient graves that predate the castle itself by centuries.

The most intact discovery was a stone-lined grave with a lintelled roof, its floor carefully paved with slabs. Though significantly disturbed over the centuries, the grave still contained the remains of what appeared to be a child or juvenile, laid to rest in the traditional Christian manner with their head facing west. Parallel to this burial, archaeologists identified traces of at least two other graves, though these had been heavily disturbed. Their fill contained a jumbled mix of human bone fragments, animal remains, and oyster shells; castle refuse that had worked its way into the ancient burials through root action and centuries of disturbance. One grave in the north-east corner had been deliberately emptied and repurposed as a drain for the tower house, suggesting the castle builders had little reverence for the existing cemetery.

These lintel-type graves are characteristic of Early Medieval Irish burial practices, indicating that when Donegal Castle was constructed, its builders chose to build atop an existing burial ground. The considerable disturbance to the graves suggests that human remains encountered during the castle’s construction may have been gathered up and reinterred elsewhere, though where remains a mystery. While excavations revealed at least five burials, the true extent of this ancient cemetery remains unknown, its boundaries hidden beneath the modern town and the foundations of the medieval castle that succeeded it.