Potsdamer Platz

Here you can get rid of your money. 

The place is one huge shopping center. Besides one of Berlin's biggest shopping malls, the "Potsdamer Platz Arkaden" there is the Sony Center and another shopping mall in the S-Bahn station.

If you're still not broke after visiting all three, you can spend the rest of your money at "Spielbank Berlin", the casino.

Potsdamer Platz is of great historic importance, but you don't see anything of it today. You find a complete history of the place at Wikipedia.