The most difficult ge­og­ra­phy of Germany riddles

Hamburg, with its 1.7 Million of inhabitants, is the second largest city after Berlin (3.4 Million). The largest urban area in Germany is the Rhine-Ruhr metropolitan region with 11M.

The 13.3 kilometres (8.3 mi) long Wuppertal Suspension Railway is the oldest electric elevated railway with hanging cars in the world. It was opened in 1901, and is still in use today as a normal means of local public transport, moving 25 million passengers annually (2008). The system was originally designed by Eugen Langen to sell to the city of Berlin, but never got there.

Situated 110 km (70 miles) from the North Sea on the river Elbe, the port of Hamburg is the second or third largest port in Europe (after the port of Rotterdam and Antwerp) and eleventh largest worldwide.

Since the end of World War II, Berlin is just 50 miles from the Polish border.