Cardiff Bay in the context of "River Ely"

51°28′12″N 3°10′23″W / 51.470°N 3.173°W / 51.470; -3.173

The Cardiff Built-up Area or Cardiff Urban Area is the name given to the urban area around Cardiff. The vast bulk of the population and area are contributed by Cardiff, which had a population of 335,145 at the 2011 census. The rest was made up by the towns of Penarth and Dinas Powys, connected to the south-west of the city along Cardiff Bay; as well as the South Wales Valleys towns of Caerphilly and Pontypridd. The total official population of this urban area was given to be 447,487 in 2011. This was an increase of almost 37% on the 2001 population of 327,706. This was mainly due to Caerphilly and Pontypridd becoming part of the built-up area. The population of the Cardiff unitary authority (not co-terminous with the built-up area or the wider urban area) in 2001 was 305,353. Cardiff Council estimated the population of the unitary authority at 317,500 in 2006; at the 2011 census it was 346,090.

Penarth (/pɛnˈɑːrθ/ pen-ARTH, Welsh: [pɛnˈarθ]) is a town and community in the Vale of Glamorgan, Wales, approximately 3 miles (4.8 km) south of Cardiff city centre on the west shore of the Severn Estuary at the southern end of Cardiff Bay.

Penarth is a seaside resort in the Cardiff Urban Area, and the second largest town in the Vale of Glamorgan, next only to the administrative centre of Barry.

The National Eisteddfod of Wales (Welsh: Eisteddfod Genedlaethol Cymru ) is the largest of several eisteddfodau that are held annually, mostly in Wales. Its eight days of competitions and performances are considered the largest music and poetry festival in Europe. Competitors typically number 6,000 or more, and overall attendance generally exceeds 100,000 visitors, the highest recently being 186,000 attending the 2024 festival in Pontypridd. The 2018 Eisteddfod was held in Cardiff Bay with a fence-free 'Maes'. In 2020, the event was held virtually under the name AmGen; events were held over a one-week period.

The Senedd building (Welsh pronunciation: [ˈsɛnɛð]), in Cardiff, houses the debating chamber and three committee rooms of the Senedd (Welsh Parliament; Welsh: Senedd Cymru; formerly the National Assembly for Wales). The 5,308-square-metre (57,100 sq ft) Senedd building was opened by Queen Elizabeth II on 1 March 2006, Saint David's Day, and the total cost was £69.6 million, which included £49.7 million in construction costs. The Senedd building is part of the Senedd estate that includes Tŷ Hywel and the Pierhead Building.

After two selection processes, it was decided that the debating chamber would be on a new site, called Site 1E, at Capital Waterside in Cardiff Bay. The Pritzker Prize-winning architect Lord Rogers of Riverside won an international architectural design competition, managed by RIBA Competitions, to design the building. It was designed to be sustainable with the use of renewable technologies and energy efficiency integrated into its design. The building was awarded an "Excellent" certification by the Building Research Establishment Environmental Assessment Method (BREEAM), and was nominated for the 2006 Stirling Prize.

The A4055 is the main road link between Cardiff Bay and Barry in Wales.