An eerie, derelict amusement park in Berlin.

This monumental work of art symbolizes the coming together of a previously divided city.

For patriotic Russians, this memorial honoring the Soviet soldiers who died liberating Berlin in 1945 is the most sacred location outside of Russia.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

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

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

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

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

An astonishingly accurate water clock that doubles as an hourly spectacle in this Berlin shopping area.

The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.

Berlin's old airport.

This obscene artwork on the side of a newspaper office pokes fun at a rival paper's former editor-in-chief.

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

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

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

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

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

A haunting contrast of trains that both saved and took the lives of Jewish children in Nazi Germany.

The most visited, and possibly most controversial, museum in Germany.

At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

Super-heavy Nazi architectural experiment.

A socialist building dedicated to teachers showcases one of the largest Soviet mosaics in the world.