Caerphilly Castle is Wales' largest and Britain's second largest castle behind Windsor. This medieval fortress was built mainly between 1268 and 1271 by Gilbert de Clare. Known as Gilbert 'The Red' because of his red hair, denoting his Norman heritage, he built the castle to take control of Glamorgan and to prevent the Welsh Prince Llewellyn ap Gruffudd from achieving his southward ambitions. The design of the castle is based on a concentric ring of walls and has an extensive ring of water defences and huge gatehouses.
This mammoth stronghold remains a striking testament to the Anglo-Norman domination of the area. Though the focus of many Welsh attacks, Caerphilly Castle has remained a formidable fortress and perhaps one of the greatest strongholds of all-time. Even the efforts of Oliver Cromwell's roundheads failed to break the Castle's boundaries, though they did leave a rather remarkable scar, the famous leaning tower which has leaned 3m out of the perpendicular since 1648.