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.

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

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

Someone loved this song enough to carve all of its lyrics onto a tree trunk in a Berlin park.

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

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

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

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

This watchtower once presided over the Berlin Wall.

A monument to the man who almost killed Hitler.

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

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

A memorial in the Tiergarten is a reminder of the suffering inflicted on homosexuals by the Nazi regime.

Dedicated to the European Sinti and Roma peoples murdered during the Holocaust.

A fascinating insight into daily life in the Eastern Bloc.

Tiny memorials honor individual victims of the Holocaust.

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

Reminders of the Battle of Berlin still scar the railway.

One of downtown Berlin's last reminders of its Communist past.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

A wunderkammer of exoticism immortalized by Tom Waits.

Hamburg's first legal sex work is relegated to a gated street that still does not allow pedestrian women.

Hamburgers are intensely proud of their tunnel beneath the river.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.