High Quality Content by WIKIPEDIA articles! The Cardiff Half Marathon (Welsh: Hanner Marathon Caerdydd) (previously known as the Cardiff Marathon) takes place in October. In 2011, it is on Sunday 16 October. It is an annual half marathon race held in the Welsh capital city of Cardiff. The event was established in 2003 and is organised by the children’s charity Barnardo’s. Also in partnership with the race is Cardiff Council, the Vale of Glamorgan Council, the Welsh Government, Welsh Athletics and sponsored by LLoyds TSB, the South Wales Echo and Princes Gate Spring Water.