The site’s religious significance stretches back to the early medieval period, when it was closely associated with Adomnán, the ninth abbot of Iona who lived from roughly 624 to 704. Best known for penning the celebrated biography of his kinsman St. Colmcille (Columba), Adomnán maintained strong connections with the monastery that once flourished here. By the 12th century, Raphoe had grown in importance to become the seat of its own diocese, marking its transition from monastic settlement to episcopal centre.

The cathedral grounds once boasted a round tower, one of those distinctive Irish medieval structures that served as both bell tower and refuge. This ancient landmark met its end in 1636;7, when Bishop John Leslie ordered its demolition to make way for his new palace. Historical sources, including John Lynch’s De Praesulibus Hibernicis, suggest the bishop’s palace was actually built directly on the tower’s foundations, literally building the new ecclesiastical power structure atop the old. Today, visitors searching for traces of the original monastery will find only two carved fragments of a door lintel, modest survivors from what was once a thriving religious community.

The current cathedral and its surroundings tell a story of continuity and change in Irish religious life. While the round tower and most of the monastery have vanished, the site remains an active place of worship, with the cathedral serving the Church of Ireland community and the historic graveyard containing centuries of local history. The archaeological record here, documented in the 1983 Archaeological Survey of County Donegal, reveals how ecclesiastical sites like Raphoe evolved through the centuries; from early Christian monasteries to medieval diocesan centres, and finally to the Protestant establishments that emerged after the Reformation.