The building visitors see today dates largely from the nineteenth century, but it incorporates fabric from an earlier seventeenth-century cathedral on the same spot, and beneath all of that lies the founding layer: an early medieval monastery attributed to St Fachtna, who died around 600 AD.

St Fachtna is associated with the foundation of the monastic community here, and the site's ecclesiastical significance appears to stretch continuously from that early Christian period through the medieval era and into the post-Reformation centuries. The cathedral that rose in the seventeenth century, and was subsequently reworked in the nineteenth, follows a pattern common to Irish church sites where successive generations of builders worked on top of, or incorporated portions of, whatever preceded them. The result is a layered structure in which different centuries sit quietly alongside one another. A graveyard also occupies the site, adding its own long accumulation of local history to the ground around the cathedral.