Barcelona's only remaining tram system takes riders to the Tibidabo funicular.

An eclectic collection of thousands of items owned by the sculptor Frederic Marès.

The unexpectedly beloved remnants of a controversial thermal power plant.

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

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

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

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

A once-secret library of Freemason history in Catalonia.

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

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

A temple to modernity, tucked away amid Barcelona's more well known museums.

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

Turntable anonymously received orphans, alms, and groceries.

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.

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

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

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

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

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

This cemetery features modernist statues as strange as its name.

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