Semi-precious Blue John stones have been mined in this cavern system for centuries.

A subterranean playground in an abandoned slate mine.

This chain of artificial lakes was an ideal test ground for the aircraft that would carry the "bouncing bombs" used by the WWII "Dambusters" squad.

A stone wall commemorates the legend of a ferocious dragon who literally got his butt kicked by a knight.

The oldest known metal-mining site in England dates back to the Bronze Age.

Mysteriously stacked storefront paths give this medieval British town an iconic style like none other.

This Welsh hotel is the spiritual home of the British 1953 Everest expedition, the first successful ascent of Mount Everest.

A corkscrew-shaped barn in Ireland.

The remains of this deep, dark mine have left behind a haunting rocky warren of tunnels.

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

These ruins are a monument to the region's industrial heritage, and the site of England's worst mining tragedy.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

What happened to the three lighthouse keepers who vanished from this place remains a mystery over a century later.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

This dreamy street will transport you to wintertime in Victorian England.

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

This 6th-century church honors St. Tudno, the patron saint of Llandudno.

Charles Dickens described the concert room in this amazing Victorian hall as "the most perfect room in the world."

Follow the original medieval paths that wind through this intriguing section of the city.

The ruins of a defunct limestone quarry still haunt this Scottish promontory.

An impressive piece of infrastructure that seems outsized when considering it serves an island with a population of less than 300.

A memorial to the acting bear whose escape caused a sensation on the Outer Hebrides.

Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".