This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

The secret medieval communication system will whisk your words above the noise of the crowd.

This abandoned viewing platform has become a monument to unnecessary government spending.

A bookstore dedicated to the intersection of comedy and art.

This generously endowed statue once stood guard outside a Roman home.

This mansion oasis contains gardens, sculptures, and fountains just off the busy Plaça Kennedy in Sant Gervasi.

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

Hidden beneath a beautiful overlook you’ll find the history of the city depicted in comic strip format next to a pay toilet.

The world's oldest bookshop still in operation.

A pair of gigantic baby heads greet passengers at Atocha Station.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

Rare wooden escalators lead deep down into an otherwise staggeringly monotonous tiled tunnel.

An unsettling sculpture of a boy hanging out in a street in Ghent has been baffling visitors for years.

A Museum of Psychiatry in a still-operating mental institution.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

From Iggy Pop to David Bowie to Nick Cave, this regal music studio has served some of the all time greats.

This classic restaurant features a gorgeous mirror-clad room.

An imperial church bombed to ruins during WWII now stands as a jagged memorial.

One of the oldest cemeteries in Germany was originally used for victims of a cholera epidemic.

This TV tower once secretly housed a GDR intelligence team.

This sprawling Jewish cemetery is one of the largest in Europe.