
The Danube is Europe's second longest river, after the Volga. It is located in Central and Eastern Europe. The Danube was once a long-standing frontier of the Roman Empire, and today flows through 10 countries, more than any other river in the world.

The Brandenburg Gate on the Luisenplatz in Potsdam, not to be confused with the gate of the same name on Berlin's Pariser Platz, was built in 1770/71 by Carl von Gontard and Georg Christian Unger by order of Frederick II of Prussia.