Cardiff (Welsh: Caerdydd), Great Britain, the capital and largest city of Wales. It is on the estuary of the Severn River. Cardiff is a seaport and the chief commercial and industrial city of Wales. It was formerly one of the world's great coal-exporting ports. The University College Cardiff, part of the University of Wales, is here. Also in Cardiff are Cardiff Castle, begun by the Normans in 1090 A.D.: a 12th-century cathedral; and the National Library and the National Museum of Wales.

Cardiff was the site of a Roman fort. The present city developed around Cardiff Castle. Growth was slow until manufacturing industries and coal exporting became important, beginning in the 19th century. Cardiff was chartered as a city in 1905 and made the capital of Wales in 1955.

Population (district): 305,349.