A marvel of Byzantine engineering under the streets of Istanbul.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

A patch of Philippines forest devoted to saving the lives of an emotionally sensitive species of googly-eyed primates.

Bohol's unusually shaped hills turn brown in the summer months.

This holy site either displays a centuries-old cross or a complete fake.

A station built to repel pirates now attracts wealthy vacationers.

Climb to the top of the world's largest seated bronze Buddha.

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

Remnants of the most densely packed city in world history, that thrived on anarchy for 30 years.

Because sometimes the most efficient route from A to B isn't a straight line.

The design of the Palacio Salvo has been described as "a lighthouse on top of a building."

Buenos Aires' city of the dead contains some very famous remains, including Eva Perón.

A bright little alley in La Boca is a part of tango history.

A desert that evokes the surreal.

This red lake 4,000 meters above sea level is home to rare flamingos.

A seemingly endless landscape of pure salt stretches far across Bolivia.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

Popular tourist destination where witches in dark hats sell dried llama fetuses for good luck.

If you’ve ever seen a picture of Machu Picchu, then you’ve seen a picture of Huayna Picchu—you just didn’t realize it.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The little bear in the "funny kind of hat" has made his way from London back to Peru.

This stone complex marks the urban center of a lost civilization.

Romania's triumphal arch looks out over Bucharest.

A striking symbol of the Bulgarian capital.