Venice's "Island of the Mad."

Super-heavy Nazi architectural experiment.

This legendary dessert was served to Nobel laureates for decades.

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

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

This secret Swiss fortress is disguised as a harmless pink house, complete with fake windows.

Artworks by loners, prisoners and the criminally insane.

A marvel of Byzantine engineering under the streets of Istanbul.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

The World Wide Web was created in this nondescript corridor at CERN.

Solar observatory doubles as a daring display of Expressionist architecture, much to Einstein's chagrin.

The music is over at the Ballhaus Riviera Ballroom, but the ballroom remains in haunting disrepair.

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

An abandoned NSA listening post on Berlin's "Devil's Mountain."

When German-Iraqi relations broke down, this embassy was vacated post haste.

An eerie, derelict amusement park in Berlin.

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

From toys to kettles to scientific instruments, this German museum celebrates the beauty of 20th century design.

This classic restaurant features a gorgeous mirror-clad room.

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

A wunderkammer of mysterious objects and stories.

A unique Holocaust memorial tells the personal stories of the Jewish residents exiled from greater Berlin.

Antique frame collection with 2,400 frames.