Elevated freight railway turned wildly successful urban park.

A Christian monastery stands on what was once a holy Incan temple.

Built on the remains of one the Incas’ most important gathering spots, this square keeps the spirit of a fallen empire alive.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

Situated on a sacred Inca site, this 16th-century cathedral took nearly 100 years to build.

These steeply terraced ruins are a stop along the Inca Trail to Machu Picchu.

Death rituals and sacrifice inside a Peruvian megalith.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

This Peruvian canyon is filled with geometric salt pools that have been being harvested since the Incan empire.

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.

Huge stone depressions which may have acted as an Incan agricultural experiment.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

A remote candy-striped mountain in the Peruvian Andes straight out of the pages of Dr. Seuss.

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

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

Cold war icon and onetime "hole" in the iron curtain.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

A fascinating insight into daily life in the Eastern Bloc.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The most visited, and possibly most controversial, museum in Germany.

The housing complex served as an anti-fascist fortress during the Austrian Civil War.

An ornate private entrance to the Vienna subway built specifically for the emperor.