Caerphilly Castle United Kingdom

Legendary

The surrounding artificial lakes make for an elaborate water defense making it difficult to attack.

Photo by Gareth Williams

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Caerphilly Castle sits inside its own artificial lake, one of the most elaborate water defense systems ever built in Britain. Attackers couldn't just march up to the walls. They had to somehow cross the water first.

The castle was built starting in 1268 by a powerful nobleman named Gilbert de Clare. He wanted to secure his control over a region called Glamorgan in South Wales.

Gilbert's biggest rival was a Welsh prince named Llywelyn ap Gruffudd. In 1270, while the castle was still being built, Llywelyn attacked and set part of it on fire.

Gilbert didn't give up. He rebuilt and finished the castle by 1271, making it stronger than before.

What made Caerphilly Castle truly special was its design. It was the first castle in Britain built from scratch with concentric walls, meaning walls built inside other walls, creating multiple layers of defense.

This design meant that even if attackers broke through the outer wall, they still had to fight their way through an entire second wall before reaching the heart of the castle. The idea worked so well that other famous castles later copied it.

At around 30 acres, Caerphilly became the largest castle in Wales and the second largest in all of Britain, smaller only than Windsor Castle.

Walk across the moat and explore the massive stone walls and round towers. Look for the castle's famous leaning tower, which tilts even more dramatically than the Leaning Tower of Pisa. Visit the Great Hall, where nobles once gathered for feasts and important meetings.