Cathays is a district and community in the centre of Cardiff, capital of Wales. It is an old suburb of Cardiff established in 1875. It is densely populated and contains many Victorian terraced houses. The area falls into the Cathays ward. It is the third most populous community in Cardiff, having a population of 18,002 in 2011.

Cardiff is the capital and largest city of Wales. Cardiff had a population of 362,310 in 2021 and forms a principal area officially known as the City and County of Cardiff. The city is the eleventh largest in the United Kingdom. Located in the southeast of Wales and in the Cardiff Capital Region, Cardiff is the county town of the historic county of Glamorgan and in 1974–1996 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. Cardiff Built-up Area covers a larger area outside the county boundary, including the towns of Dinas Powys and Penarth.