A strange and ancient landscape hides the dark, cavernous remains of a 5,000-year-old flint mine.

This unique rock formation is quite the local celebrity, although one day it may come crashing down.

According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

This center tells the story of one of the most famous battles in Irish history.

The ancient tomb acts as a calendar that keeps perfect time.

Old-fashioned knowledge and modern engineering create the world's only rotating boatlift.

Cascading waterfalls mark the gateway to the ancient burial place of Clan Macnab.

Possibly the oldest living thing in Europe, more likely a pagan survivor.

Also known as “Robin Hood’s tree,” it became a famed location along Hadrian's Wall before it was cut down.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

These planks were originally installed to hold the dead.

English parliaments were once convened by this ancient oak tree in the heart of Sherwood Forest.

This iconic Peak District ridge was once one of the busiest roads in medieval Britain.

The nearly 200-year-old folly has a secret spiral staircase hidden in one of its pillars.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

In this medieval fish bowl, the carp weren't pets.

This hill and tower are steeped in legend, from King Arthur to the Holy Grail.

A dark Victorian well house now plays host to mystical waters and pagan shrines.

The massive, original Colgate Clock is mounted on a defunct factory building that was once a prison.

An unusual round church in London with a Templar past.

It was once nicknamed "the most bombed hotel in Europe."

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

This stunning concert hall has become a symbol of Iceland's national recovery.