The site’s religious significance stretches back to Adomnán, the ninth abbot of Iona who lived from around 624 to 704. Best known for writing the biography of his kinsman St. Colmcille, Adomnán had close ties to the monastery that once stood here. By the 12th century, Raphoe had grown in importance to become a diocesan see, marking its transition from monastic settlement to episcopal centre.

The monastery once boasted a round tower, that distinctive feature of Irish ecclesiastical sites, but it met an unfortunate end in 1636–7 when Bishop John Leslie demolished it to build his palace. According to John Lynch’s De Praesulibus Hibernicis and later scholarly work, the bishop’s palace was constructed directly on the site where the tower had stood for centuries. Today, virtually nothing remains of the original monastery except for two remarkable pieces of a sculptured door lintel that offer a tantalising glimpse into the site’s medieval past.

These carved stone fragments, possibly dating from the ninth or tenth centuries though potentially later, depict scenes from Christ’s Passion with remarkable detail. The left section, now preserved in the cathedral’s vestibule, shows the arrest of Christ with St. Peter cutting off the ear of Malchus, the High Priest’s servant, whilst a kneeling soldier with a lance appears in the lower right corner, possibly representing Longinus. The right half of the lintel, set into the external north wall of the nave, bears the weathered remains of a crucifixion scene complete with a winged figure and traces of another soldier who may be Stephaton, the chalice bearer. Though time has worn away much of the intricate carving, these fragments remain as the sole visible testament to Raphoe’s ancient monastic heritage.