The hidden medieval world buried beneath a castle

[Gerald]

At first sight, there is little clue to the secrets that lie beneath the Château de Brézé in France. Below the surface of this impressive castle lies a deep network of tunnels and rooms that form one of Europe's largest underground fortresses.

Much like the billionaires of today, the lords of this castle carefully constructed themselves a medieval 'doomsday bunker' to provide themselves with shelter and protection in the face of invasion or disease.

Video by Mathieu Orcel and Augustin Muniz

https://www.bbc.com/reel/playlist/se...?vpid=p08b8d1n

An extensive and very complex underground building ... there are many of these around the world.