Bold black and white motifs of life and death add a dramatic flair to this 17th-century crypt.

A Spanish town built into the cliffs.

Moorish signal station on a stratgic rocky outcrop.

A house covered entirely with shells.

Rare karst landscape eroded from a flat seabed.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

This semi-secret storybook hedge maze is also the oldest garden in the city.

A beautiful but toxic fountain of mercury.

This massive underground salt mine now holds a sci-fi theme park in its depths.

The world's longest outdoor covered escalator system transports commuters through Hong Kong's hilly terrain.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

If you've ever wanted to tear Hello Kitty apart with your teeth, this is the place.

The tallest outdoor elevator in Europe rockets passengers on a dizzyingly precarious ride to the top of a mountain.

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

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.

Figures of unknown origin carved into the surfaces of underground caves.

Beautiful carved tunnels.

An aluminum skeleton brings Chinese mythology to the French shore.

A self-built mosaic house and sculpture park.

Folklore and history carved into Brittany's coast.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A darkly erotic open-air statuary in Catalonia.