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

A former steam-powered mill from the 1800s is now an industrial park with a giant steel dragon slide.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

This Funeral Hearse Museum represents the finest in cadaver transportation.

One of Europe's largest supercomputers is housed inside of a disused chapel.

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

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

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

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

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

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

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

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

This cemetery features modernist statues as strange as its name.

A beautiful but toxic fountain of mercury.

This semi-secret storybook hedge maze is also the oldest garden in the city.

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.

Hidden behind a wall, Spanish nuns distribute their signature sweets on a revolving tray.

Its appearance in "Game of Thrones" may spur on the long-awaited restoration of this medieval shipyard.

An eerie collection of the surviving structures from a past celebration of the future.

A 16th-century Andalusian palace.

This former charity hospital for elderly clergy houses some of Seville’s most treasured paintings.

The world's largest wooden structure.