This wooden hotel is a temple to German sustainability and forest conservation.

Hamburgers are intensely proud of their tunnel beneath the river.

Remnants of an exploded schooner and wrecked submarines form a breakwater.

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

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

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

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

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

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

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

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

A slice of central Asia in the middle of 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.