Mysterious Spanish catacombs of unknown origins.

Whether they are bulls or pigs, these ancient animal sculptures are fascinating relics.

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

An accidental trick of light casts the perfect shadow of a pilgrim of the Camino de Santiago against the cathedral wall.

Thanks to an acoustic anomaly, this unassuming stone bench has heard one hundred years of secrets.

Devastated landscape used for hundreds of years by the Romans as their primary mining site.

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

The final resting place of the great navigator, or maybe his brother.

The world's largest wooden structure.

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

Ancient catacombs form the foundation for this Rococo orgy of a church.

One of the few places in Portugal where the Celtic ritual of wearing large wooden masks is still practiced.

An old wool-washing house filled with Fluxus contemporary art.

You can cross from one country to another in a single hop on this little bridge.

A botanically themed auditorium blooms within the world’s last operating double-decker theater.

Albert Einstein's head sticks out of a snail shell stacked on a rocket in this truly bizarre monument to the scientist.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

A fairytale island floats in the middle of Italy's little-known Lake Orta.

The ornate miniature mansions were built for Istanbul's feathered residents.

A strange rock with a sinister reputation lurks within the crimson waters of this Scottish glen.

A futuristic hovertrain is parked unceremoniously alongside a nondescript road.

This abandoned stepwell is one of the largest, deepest, and certainly one of the creepiest in India.

The Andean town where every single building is decorated with a brightly colored frieze.