A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

A surreal museum of extraordinary industrial objects.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

Started as a kitchen garden, now the second largest botanical garden in the world.

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

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

An eerie, derelict amusement park in Berlin.

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

This giant crucifix is like U2's Joshua Tree for Swedish death metal fans.

No one knows who's responsible for decorating this tunnel with stuffed animals, but the people love it enough to protest their removal.

Street artists transformed this abandoned industrial neighborhood into one of Europe's largest graffiti exhibitions.

A man has revenged his true love's betrayal through tears and stone genitalia.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

The internet as provided by a James Bond villain.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

Dine amidst exotic plants at this former royal greenhouse.

The townhouse where the "Blood Countess" Elizabeth Báthory started her murderous career.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

This former insane asylum now holds a pathological anatomy museum.

Macabre museum devoted to historical Viennese murders.