In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A psychedelic labyrinth on the San Francisco bay.

A huge musical instrument played by the ocean.

Infamous and now demolished panopticon prison built by its former inhabitants.

Strange masks and obscure costumes are housed in this old Madrid corrala.

An iconic and controversial ancient Iberian funerary urn with a hauntingly penetrating gaze.

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.

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

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

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

Commonly acknowledged as the only public monument to the Devil himself.

A lush indoor jungle fills this bustling Madrid transportation hub.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

Bored potato-guarding Nazis etched their thoughts onto a brick storage building in Copenhagen's Meatpacking District.

A novel collection of medical curiosities housed in an 18th-century surgeon training academy.

Museum on earth sciences featuring a recreation of a famous curiosity cabinet.

A collection of noses tucked inside an art museum reveals how times have changed.

Opulence and fantasy collide in this royal chair which is supposedly made with unicorn horns.

Hans Christian Andersen for the postmodern world.

A walkable map of the world, made from soil and stone by one man.

This sublime architectural marvel is a rare example of an expressionist church.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Six beautiful wooden giants are hidden around Copenhagen.