Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Visit a surreal landscape so otherworldly NASA actually used it to train the Apollo 17 crew.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

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.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

A whimsical bridge adorned with decorative dragons.

This one-time health resort was used by aristocrats around the world.

A miniature train-ride through Slovenia's largest cave system.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

The celebrated eyesore created by starry-eyed sweethearts.

Thousands of flamingos and other bird species flourish in these Camargue wetlands.

Lady Liberty's original designer installed a little clone in this French fountain.

Walk through living pictures and music in the Cathedral of Images.

French commune at the heart of conspiracies.

This ancient theater was once the home of fierce gladiatorial battles.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

This bridge was constructed from the rubble of the infamous Bastille.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.