The Cathedral lies in the ancient “City of Llandaff” much of which is now a conservation area. Despite being surrounded on all sides by the bustling modern city of Cardiff, the Llandaff conservation area remains comparatively unspoilt and surprisingly tranquil.
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. 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. For 200 years following the reign of King Henry VIII the building fell into a state of near-ruin. However, in the early nineteenth century, new life and growing prosperity in the Diocese made possible a fresh restoration undertaken by J F Seddon and John Pritchard. To them we owe much of the present structure including the South West tower and spire, completed in 1869.
https://www.visitcardiff.com/highlights/llandaff-cathedral/