Europe's largest natural bridge has a 19th century royal chateau built into its side.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

Macabre astrological automaton clock dating to the late 1400s.

A church of bones, decorated with 40,000 human skeletons.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

A marvel of Byzantine engineering under the streets of Istanbul.

The ruins of an early-18th-century complex that could once house up to 12,000 horses.

Morocco’s modern capital was once a haven for Barbary pirates, who went so far as to establish a republic of their own.

Designed as a labyrinth, this subterranean prison was crafted without bars or doors.

The courtyard of this small Marinid madrasa is a dazzling example of intricate Islamic architecture.

This former royal palace with gorgeous gardens became the first museum in Morocco.

Traditional 11th-century outdoor tannery.

Crumbling necropolis set high above Fez.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

The other side is actually green.

Mosaics, storks, and brothels—this ancient city has it all.

Art Deco stylings conceal the true nature of this bridge.

One of the oldest producers of hand-folded fortune cookies still uses its original secret recipe.

Golden Gate Park's historic collection of plants.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

This cathedral hides a sculpted dog that determines your fate and an unexploded shell from World War II.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

An historic and oft-filmed spot for musclebound iron pumpers on the Pacific coast.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.