A gorge full of caverns where early humans lived alongside cave hyenas, giant mammoths and wooly rhinoceroses.

This beautiful "lagoon" is actually a toxic soup filled with cars, carcasses, and trash. When warnings couldn't stop people from going for a dip, the town dyed it black.

This stone throne invites adventurers to observe breathtaking views of the Peak District.

This tiny little pool is said to be home to a malicious mermaid named Jenny Greenteeth.

A hidden tunnel leads to an abandoned slate quarry that's now a secret swimming spot guarded by cliffs.

This 19th-century island fort built to protect against an invasion by sea.

An amazing collection of curiosities hidden in a small Welsh village.

An unexpectedly extraterrestrial room in a former Victorian resort club.

After years of slow decline, a derelict Gothic castle is now being restored to life.

One family's environment-friendly hobbit-house in Wales.

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

This abandoned asylum in Wales might look haunted, but it's still beautiful.

The decaying ruins of Wales' first asylum for the mentally ill.