Caerphilly Castle is a medieval castle that dominates the centre of the town of Caerphilly in south Wales. It is the largest castle in Wales and the second largest in Britain after Windsor Castle. Built mainly between 1268 and 1271 to stop Llywelyn ap Gruffudds southward ambitions, it is an early example of a concentric castle with extensive water defences.
The castle deteriorated during several centuries of disuse. Its owners since 1766, the Marquesses of Bute undertook extensive restoration. During the 1930s, surrounding streets were levelled to restore the dominant view which had been obscured by town development. In 1950, the castle and grounds were handed over to the British government.