This 17th-century structure is a beautiful testimony to traditional Persian architecture

The 20-mile causeway that separates the Netherlands from the sea.

This medieval city gate is now a blend of the past and the modern world.

San Gennaro, the patron saint of Naples, greets pedestrians between these narrow city streets.

The first declared National Monument in the United States.

This castle-fortress is a living example of the transition from medieval defenses to modern fortifications.

The world's first electric battery-powered submarine.

An ancient Roman theatre restored to its former glory in the Spanish city of Cartegena.

An enchanting landscape of ancient sandstone structures eroded into otherworldly shapes.

The oldest continuously occupied public building in the United States.

Two nearly identical Chinese pagodas stand side by side, along with ancient stone relics.

The western-most fortress on the Great Wall of China has gone from a strategic stronghold to a kitschy tourist carnival.

Hundreds of caves filled with thousands of centuries-old statues and murals.

Enormous burial mounds of ancient emperors.

Hidden behind musical flora and forgotten for over a thousand years, this cave is now a neon dream.

Ming Dynasty necropolis raided during the Cultural Revolution.

This Tang Dynasty behemoth is the biggest Buddha in the world.

Why walk on this historical site when you can zoom down instead?

The most famous location in China was home to whole dynasties worth of imperial rulers.

The chefs at El Diablo use heat generated by an active volcano to cook the food.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

In the fictional world of Kcymaerxthaere, celestial wonders marked a portal to a powerful route of travel at this site in Madrid, Spain.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

This 47-story "M" needed 20 years to be completed