Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

This cutting edge museum details the history of skiing, from its ancient origins to its status as a sport.

Venice's "Island of the Mad."

Inside this museum, visitors venture through ghost stories entrenched in Icelandic folklore.

A sweet museum focused on beets.

An old department store turned Nazi prison turned artist commune.

This natural "sea of stones" was once used by the Romans as a quarry.

One of the oldest student jails in Germany.

One of the largest busts in the world celebrates the German city's erstwhile namesake.

This proud Teutonic warrior rises out of a German forest heralding a victory and measuring lightning.

A spitting ode to a German serial killer.

This small exhibition displays equipment and artifacts once belonging to the feared Stasi secret police.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

This incredible stone temple is a monument to death, victory, and fantasy architecture.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

An eerie, derelict amusement park in Berlin.

A magnificent collection of imperial armor and weaponry.

Museum devoted to the artificial language of Esperanto.

Apartment complexes built into huge repurposed natural gas tanks.

This museum promotes informed contraception by documenting its often secret past.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

This large cave is a summer home to thousands of bats and has a rich history dating back to prehistoric times.

A collection of full-size movie monsters opened to the public.

Along the Rhine, about a mile from the historic Munster, learn the heartrending story of two lovers torn asunder, cast into unknown layers of time and space.