Cathedral of Saint Andrew

Saint Senan's Cathedral or Saint Andrew's Cathedral. This seat of the Bishop of Dhassa was named for Saint Andrew Senan, a holy martyr of the 4th century.  
It was here that the Curia of the Church of Gwynedd met on the 28th day of March in the year 1121 to pronounce a bill of excommunication against Alaric Morgan Duke of Corwyn and Father Duncan McLain. The Duke of Corwyn and Father McLain were received back into the communion of the Holy Church some 3 months later, on the 21st day of June. [Deryni Checkmate; High Deryni; The Bishop's Heir].