Cardiff (Caer-Taff, 'fort of the Taff'), a municipal, parliamentary, and county borough and seaport, the county town of Glamorganshire, South Wales, on the river Taff, a new bridge over which was opened in 1890 by the Duke of Clarence, 56 miles SW. of Gloucester, and 170 W. of London. Its progress in recent years is the most remarkable, the population rising from 2000 in 1801 to 10,077 in 1841, 82,761 in 1881, and 164,420 in 1901. Since 1905 the mayor is called Lord Mayor. An ancient municipal borough, with Cowbridge and Llantrissant, it returns one member to parliament. Among the public buildings are the infirmary, town-hall, free library and museum, jail, law-courts, county buildings, the university college for South Wales (1883), the Roman Catholic pro-Cathedral, baths, a theatre, and numerous halls. There is a public park.

The port of Cardiff is the outlet for the large mineral and manufactured produce of the central portion of the South Wales mineral-field, in which are the populous districts of Merthyr-Tydvil, Rhymney, Aberdare, and the Rhondda Valley. The town is also one of the chief stations on the Great Western line from London to Milford-Haven. The Bute Docks, with an area of 150 acres, constructed at the expense of the Bute estate, have cost nearly four millions sterling, and belong to the Marquis of Bute. There is also a tidal harbour, with a low-water pier 1400 feet in length. The imports to Cardiff include copper ore, live cattle, salted provisions, foreign fruit and vegetables, corn and flour, etc. The Penarth Docks, about one mile to the westward, form another outlet for the trade of the district. The Barry Dock (1888), of nearly 80 acres, adds enormously to the shipping facilities of Cardiff. Steamers ply between the port of Cardiff and New York, London, Liverpool, Glasgow, Bristol, Cork, Whitehaven, and Burnham. The growth of Cardiff began with the opening of the canal from Merthyr-Tydvil to the sea (1794); the first dock was opened only in 1839; the second or East dock dates from 1854. The corporation, which has spent 500,000 in improving the streets, in 1879 acquired the water-works, and in 1888 secured a new supply from the Brecknockshire Beacons, at a cost of nearly 600,000.

The ancient city of Llandaff (q.v.), now a mere village, is almost connected with Cardiff. Cardiff Castle (1110) is partly now in ruins, and partly occupied by the Marquis of Bute, who has spent large sums in rebuilding it, and to whom nearly the whole of the modern town belongs. Robert, Duke of Normandy, died in the castle, after twenty-eight years' captivity; and Cromwell (1648) got possession of it through treachery.