The hill above the town of Downpatrick in County Down is known in Irish as Dún Pádraig — the fort of Patrick — and the tradition that St Patrick died and was buried there stretches back to the early medieval period. The earliest sources place his death at Saul, a few miles away, where his confessor Tírechán wrote that the ox pulling the saint's funeral cart refused to move until it reached a small hill near Downpatrick, where Patrick was laid to rest. An eighth-century hymn by St Fiacc identifies a 'fertile fountain' near the burial site — almost certainly the well complex at Struell — suggesting the sacred geography of Downpatrick was well-established within three centuries of Patrick's death in the 5th century.
The story
The gathering of three saints under one stone is attributed to the Anglo-Norman knight John de Courcy, who conquered Ulster in 1177 and sought to establish his legitimacy through conspicuous patronage of Irish sacred sites. According to the tradition recorded by Jocelin of Furness in his Life of Saint Patrick (1185), de Courcy had the relics of St Brigid transferred from Kildare and those of St Columba from Iona, then interred them together with Patrick's remains on Cathedral Hill. From this act of relic-assembly grew the famous couplet that became a pilgrimage formula across the Gaelic world: 'In Down three saints one grave do fill — Patrick, Brigid and Colmcille.'
The modern grave marker — a large granite slab inscribed simply 'Patrick' with a Celtic cross — was placed on Cathedral Hill in the early twentieth century to protect the traditional burial spot from pilgrims who had been scooping earth from the site to take with them on emigrating, a practice of devotional material culture that testifies to the depth of attachment the legend inspired. Down Cathedral (Church of Ireland) stands on the hill today and the grave remains a focus of continuous pilgrimage, especially on St Patrick's Day. The Atlas Obscura entry for the site and the St Patrick's Centre in Downpatrick both document the tradition in detail. The legend of the triple burial — whatever its historical accuracy — gave County Down a symbolic centrality in Irish Christian memory that it has never lost.