Presiding over thirty acres, Caerphilly Castle is the second largest in Britain. A dramatic fortress, its tower leans more than Pisa’s and is frequented by the Ghost of the Green Lady. In the heart of the Caerphilly, it dominates the town as it would have done in the thirteenth century. Never defeated by the Welsh, it held back Welsh Prince Gruffydd ap Llywelyn with its concentric circle system and impressive water defenses. Visitors can now wander its grounds with the resident geese.