Rippling sand dunes frozen in the Arizona rock.

A psychedelic labyrinth on the San Francisco bay.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

An abandoned horror film set sits eerily along a highway through Hollywood's "door to the desert."

Along the most northwestern point in Africa is an ancient cave surrounded by legends.

Founded as a refugee camp, now a popular tourist spot.

The largest madrasa in Morocco once housed more than 900 students within its exquisite walls.

The oldest monument in Marrakesh and the city's only surviving example of Almoravid architecture.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

A Moroccan getaway in the mountain range that plays the Himalayas' stunt double.

It took 40 years to build this Eden-like garden in Marrakech, later restored by Yves Saint-Laurent.

This colorful statue welcomes visitors to a Barcelona park.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

An eclectic collection of thousands of items owned by the sculptor Frederic Marès.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

The gigantic skull of a long-extinct species that once roamed the forests of England and Ireland.

These morbid carvings remind churchgoers of the inevitability of death.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

Catacombs turned marketplace.

This South London cemetery holds the remains of more than 15,000 people.

This Funeral Hearse Museum represents the finest in cadaver transportation.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.