This chest hospital with a dark, haunted past serves as a fitting set for horror films and a paradise for ghost hunters.

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

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

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

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

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.

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

The abandoned ruins of a beautiful medieval castle just outside Barcelona.

A science fiction-inspired apartment building designed by a famous Spanish architect.

An architect transformed this abandoned cement factory into his castle-like workshop.

This imposing modern citadel started out as a home renovation project.