This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

Baroque celebration of the end of the Great Plague of Vienna.

The Habsburgs' royal collections of art and wonders.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

Berlin's old airport.

Where once there was a train station bathroom, there is now this German burger joint.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

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

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

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

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

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

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

A slice of central Asia in the middle of Berlin.

Catacombs turned marketplace.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Giant, friendly pelicans in Central London, the most unlikely of places.

The only surviving prototype for Buckminster Fuller's house of the future.

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.