One of the largest ossuaries in Spain is packed from floor to ceiling with bones.

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

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

One of the world's oldest universities houses an incredible collection of anatomical models, mummified body parts, and human bones.

This magical space partly designed by Antoni Gaudi is one of the best examples of romantic gardening in the Mediterranean.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

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

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

The chefs at El Diablo use heat generated by an active volcano to cook the food.

This massive fiberglass Gulliver turns every visitor into a Lilliputian.

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

A once-secret library of Freemason history in Catalonia.

Stunning Roman aqueduct used for 1900 years and still standing.

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

A completely underwater art museum sends a stark message about humans' impact on the environment.

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

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

The final resting place of the great navigator, or maybe his brother.

The morbid items in this small and hidden museum are not for the weak stomached.

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

A Spanish forest is filled with mysterious stone carvings.

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.