This amazingly preserved Doric temple was abandoned before it was ever completed.

A madman's personal garden filled with 1,000 sculpted heads.

The world's brightest bioluminescent bay.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

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

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

Bathe in these natural hot springs located high in the Andes Mountains.

Death rituals and sacrifice inside a Peruvian megalith.

Did Inca children also slide down these smooth rocky slopes above Cusco?

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

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

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

A painting in the historic Cathedral Basilica depicts Jesus and his disciples dining on a traditional Peruvian menu.

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

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

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

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

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

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

A lush indoor jungle fills this bustling Madrid transportation hub.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

An ancient Egyptian temple in the middle of Madrid, Spain.