A once-secret library of Freemason history in Catalonia.

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

A temple to modernity, tucked away amid Barcelona's more well known museums.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

A stately palace has been converted into the world's largest cannabis museum.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

A unique waterfall that some believe attracts the fairfolk.

The world's largest collection of witchcraft regalia.

These mysterious mazes carved on the rock may be up to 4,000 years old.

This tangled English forest looks like something right out of a fairytale.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

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

The undercroft is a spectacular example of medieval Cistercian architecture.

This English medieval castle is where King John died of dysentery.

Once a palace for the Archbishop of York, these 15th-century ruins now serve as a haunt for history buffs.

This muddy wooded valley and the ancient structures it hides are said to be the favored haunt of the legendary Friar Tuck.

An enigmatic natural rock formation with a manmade passage cut through the center.

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

A mysterious medieval monument said to mark the final resting place of Robin Hood’s henchman.

The ancestral home of beloved English poet Lord Byron has a bizarre history.

This romantic, decaying 13th-century ruin on the edge of Sherwood Forest is reputedly one of England's most haunted places.