Cardiff is the capital and largest city of Wales. Cardiff had a population of 381,516 in 2025 and forms a principal area officially known as the City and County of Cardiff (Welsh: Dinas a Sir Caerdydd). The city is the eleventh largest in the United Kingdom. Located in the southeast of Wales, the city sits within the Cardiff Capital Region, which consists of 1.5 million people, accounting for roughly half the nation's total population. Cardiff is the county town of the historic county of Glamorgan and from 1974 to 1996 of South Glamorgan. It belongs to the Eurocities network of the largest European cities. A small town until the early 19th century, its prominence as a port for coal when mining began in the region helped its expansion. In 1905, it was ranked as a city and in 1955 proclaimed capital of Wales. The Cardiff urban area covers a larger area outside the county boundary, including the towns of Dinas Powys and Penarth.
Cardiff is the main commercial centre of Wales as well as the base for the Senedd, the Welsh Parliament. At the 2021 census, the unitary authority area population was put at 362,400, an increase of 4.7% compared to the 2011 census when the population was 346,100. The population of the wider urban area in 2011 was 479,000. In 2011, it ranked sixth in the world in a National Geographic magazine list of alternative tourist destinations. It is the most popular destination in Wales with 21.3 million visitors in 2017. It was voted as the best city in the UK in the 2023 Readers' Choice Awards.
Cardiff is a major centre for television and film production (such as the 2005 revival of Doctor Who, Torchwood and Sherlock) and is the Welsh base for the main national broadcasters.
Cardiff Bay contains the Senedd building and the Wales Millennium Centre arts complex. Work continues at Cardiff Bay and in the centre on projects such as Cardiff International Sports Village, BBC drama village, and a new business district.
Caerdydd (the Welsh name of the city) derives from the Middle Welsh Caerdyf. The change from -dyf to -dydd shows the colloquial alteration of Welsh f [v] and dd [ð] and was perhaps also driven by folk etymology. This sound change probably first occurred in the Middle Ages; both forms were current in the Tudor period. Caerdyf has its origins in post-Roman Brythonic words meaning "the fort of the Taff". The fort probably refers to that established by the Romans. Caer is Welsh for fort and -dyf is a form of Taf (Taff), the river which flows by Cardiff Castle, with the ⟨t⟩ showing consonant mutation to ⟨d⟩, as is normal in compound words, and the vowel showing affection as a result of a (lost) genitive case ending.
The anglicised Cardiff is derived from Caerdyf, with the Welsh f [v] borrowed as ff , as also happens in Taff (from Welsh Taf) and Llandaff (from Welsh Llandaf).
The antiquarian William Camden (1551–1623) suggested that the name Cardiff may derive from *Caer-Didi ("the Fort of Didius"), a name supposedly given in honour of Aulus Didius Gallus, governor of a nearby province at the time when the Roman fort was established. Although some sources repeat this theory, it has been rejected on linguistic grounds by modern scholars such as Professor Gwynedd Pierce.
Archaeological evidence from sites in and around Cardiff show that people had settled in the area by at least around 6000 BC, during the early Neolithic: about 1,500 years before either Stonehenge or the Great Pyramid of Giza was completed. These include the St Lythans burial chamber near Wenvoe, (approximately four miles or six km west of Cardiff city centre); the Tinkinswood burial chamber, near St. Nicholas (about six miles or ten km west of Cardiff city centre), the Cae'rarfau Chambered Tomb, Creigiau (about six miles or ten km northwest of Cardiff city centre) and the Gwern y Cleppa long barrow, near Coedkernew, Newport (about eight miles or thirteen km northeast of Cardiff city centre). A group of five Bronze Age tumuli is at the summit of the Garth, within the county's northern boundary. Four Iron Age hill fort and enclosure sites have been identified within Cardiff's county boundaries, including Caerau Hillfort, an enclosed area of 5.1 hectares (12+1⁄2 acres).
Until the Roman conquest of Britain, Cardiff was part of the territory of the Silures – a Celtic British tribe that flourished in the Iron Age – whose territory included the areas that would become known as Breconshire, Monmouthshire and Glamorgan. The 3.2 ha (8-acre) fort established by the Romans near the mouth of the River Taff in AD 75, in what would become the north western boundary of the centre of Cardiff, was built over an extensive settlement that had been established by the Romans in the 50s AD. The fort was one of a series of military outposts associated with Isca Augusta (Caerleon) that acted as border defences. The fort may have been abandoned in the early 2nd century as the area had been subdued. However, by this time a civilian settlement, or vicus, was established. It was likely made up of traders who made a living from the fort, ex-soldiers and their families. A Roman villa has been discovered at Ely. Contemporary with the Saxon Shore forts of the 3rd and 4th centuries, a stone fortress was established at Cardiff. Similar to the shore forts, the fortress was built to protect Britannia from raiders. Coins from the reign of Gratian indicate that Cardiff was inhabited until at least the 4th century; the fort was abandoned towards the end of the 4th century, as the last Roman legions left the province of Britannia with Magnus Maximus.
Little is known of the fort and civilian settlement in the period between the Roman departure from Britain and the Norman Conquest. The settlement probably shrank in size and may even have been abandoned. In the absence of Roman rule, Wales was divided into small kingdoms; early on, Meurig ap Tewdrig emerged as the local king in Glywysing (which later became Glamorgan). The area passed through his family until the advent of the Normans in the 11th century.
Norman occupation and Middle Ages
In 1081 William I, King of England visited Cardiff as part of an armed pilgrimage across South Wales and ordered work to begin on the castle keep within the walls of the old Roman fort. Cardiff Castle has been at the heart of the city ever since. The castle was substantially altered and extended during the Victorian period by John Crichton-Stuart, 3rd Marquess of Bute, and the architect William Burges. Original Roman work can, however, still be distinguished in the wall facings.
A town grew up under the castle, consisting mainly of settlers from England. Cardiff had a population of between 1,500 and 2,000 in the Middle Ages – a normal size for a Welsh town in the period. It was the centre of the Norman Marcher Lordship of Glamorgan. By the end of the 13th century, Cardiff was the only town in Wales with a population exceeding 2,000, although it remained relatively small compared with notable towns in England and continued to be contained within its walls, which were begun as a wooden palisade in the early 12th century. It was of sufficient size and importance to receive a series of charters, notably in 1331 from William La Zouche, Lord of Glamorgan through marriage with the de Clare family, Edward III in 1359, then Henry IV in 1400, and later Henry VI.
In 1404, Owain Glyndŵr burned Cardiff and took possession of the Castle. As many of the buildings were made of timber and tightly packed within the town walls, much of Cardiff was destroyed. The settlement was soon rebuilt on the same street plan and began to flourish again. (Glyndŵr's statue was erected in Cardiff Town Hall in the early 20th century, reflecting the complex, often conflicting cultural identity of Cardiff as capital of Wales.) Besides serving an important political role in the governance of the fertile south Glamorgan coastal plain, Cardiff was a busy port in the Middle Ages and declared an English staple port in 1327.
In 1536, the Laws in Wales Acts 1535–1542 led to the creation of Glamorganshire and Cardiff was made the county town, it also became part of Kibbor hundred, around the same time the Herberts became the most powerful family in the area. In 1538, Henry VIII closed Cardiff's Dominican and Franciscan friaries, whose remains were used as building materials. A writer in this period noted: "The River Taff runs under the walls of his honours castle and from the north part of the town to the south part where there is a fair quay and a safe harbour for shipping."