Llandaff Cathedral stands on one of the oldest Christian sites in Britain. In the sixth century St Dyfrig founded a community close to the ford where the Roman road crossed the river Taff. He was succeeded by St Teilo and then Teilo's nephew, St Euddogwy. These three Celtic Saints remain patron saints of the present Cathedral and are represented by the three mitres in the Cathedral badge. Nothing remains of the original church but a Celtic Cross that stood nearby can still be seen near the door of the Chapter House.
The present cathedral dates from 1107 when Bishop Urban, the first Bishop appointed by the Normans, instigated the building of a much larger church. The arch behind the High Altar was built at that time and the doorway that now leads to the St David (or Welsh Regiment) Chapel may have been the West door of Urban's church until it was moved to its new site when the Cathedral was extended and widened and a new West front built about 1220. This West front is judged by many to be one of the two or three most notable mediaeval works of art in Wales.