These medieval tunnels provided water to the city above through centuries of civil war and plague.

The remains of centuries of copper mining appear like an alien landscape.

This former quarry is now a vibrant labyrinth of magical in situ sculptures.

This ancient bridge made of stone slabs is said to be reserved for the devil to sunbathe.

This neolithic stone grave has been altered and restored so often its now more neo than lithic.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

The stately remains of Llywelyn the Great's mighty fortress.

The oldest continual pilgrimage site in Britain was supposedly created by a gruesome beheading.

After mysteriously refusing to surrender at the end of World War II this sunken submarine was only salvaged in a search for Nazi gold.

19th century tunnels burrowed under Liverpool.

The largest preserved walking dragline excavator in Western Europe.

The longest and tallest aqueduct in Britain can actually be sailed across.

A 550-square-meter micro-nation off the coast of Britain.

This haunting stone chasm is a hotbed of mossy rock and English legend.

The mouldering remains of a disgraced British children's icon are hidden in the brush of a public park.

A house of bones — but nobody is quite sure to whom they belong.

Huge concrete structures designed as an early warning system for Britain to detect enemy aircraft.

Surreal riveted sea forts once protected the Kent shores from German attack.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

An intriguing three-sided folly is a testament to one man's devotion to Catholicism and the number three.

The Bristol Camera Obscura housed in an ancient windmill.

This crumbling headstone commemorates the first death by tiger in Britain's history.

This colossal war machine is now a living museum dedicated to underwater warfare.

The remnants of a strange stilted building on rails can still be seen at low tide.