A graveyard for early settlers, sometimes called Old Pioneer Cemetery, hidden in the woods on a hillside.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

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

Week-long block party becomes a competition for the best decorated street.

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.

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

Barça football fans might see the insignia hidden in a church window as a divine sign.

An early 20th-century bullring converted into a modern shopping center.

A once grand hotel now sits eerily abandoned in the Catalan countryside outside Barcelona.

Turntable anonymously received orphans, alms, and groceries.

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

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

Mountain where Jesus was first tempted by the Devil.

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.

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

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

Enormous sandstone towers loom within a Czech forest.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.