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

One of the most photographed buildings in a city known for its Modernista architecture is an abandoned squat.

Bask in the 19th century grandeur of an eccentric Freemason millionaire's private gardens.

A beautiful but toxic fountain of mercury.

A daily pyrotechnic celebration marks a beloved tradition during Valencia's festival season.

The odd cement nubs littering this Spanish square are actually the entrances to a series of buried silos.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

Bacteria and algae give the salty water its bubblegum hue.

Originally planted by the ancient Carthaginians, this sprawling palm grove is one of the largest in the world.

A well-restored ancient archaeology site gives a real feel for life during the Roman age.

Fascinating exhibits of prehistoric and ancient artifacts displayed with a uniquely modern touch.

A celebration of solstice followed by a fiery purging of evils.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

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

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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