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.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

A Franco-era dam flooded (almost) everyone out of this centuries-old Aragonese town.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

This awesome Spanish castle is so fantastical it was actually used on Game of Thrones.

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

Considered the birthplace of the Copper Age and Bronze Age, the river is tinted red from 5,000 years of mining.

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

A gravity-defying "devil's bridge" that has a surprising architectural feature for its stability.

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

Village situated on a narrow volcanic escarpment.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.

This house's itty bitty size means no humans allowed.

This Funeral Hearse Museum represents the finest in cadaver transportation.

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

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.

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.

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

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

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

A stately palace has been converted into the world's largest cannabis museum.

Mountain where Jesus was first tempted by the Devil.

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