Caerphilly Castle, covering an area of 30 acres, is the largest castle in Wales and one of the biggest in all of Britain.

In 1268, 'Red Gilbert' de Clare, Lord of Glamorgan, began building the castle to defend contested land during his conflict with Llywelyn ap Gruffudd, Prince of Wales. The castle is a magnificent example of a medieval concentric design, with the curtain wall of the inner central ward surrounded by an outer curtain wall which is surrounded by water defences and in some places by even more walls.