Duisburg is located in the western part of Germany's Ruhr Area at the confluence of the Rhine and Ruhr rivers. It was (and is) an industrial center, known for its iron and steel production. The city was almost completely destroyed during World War II, so it doesn't resemble the picture on the card anymore.
Duisburg currently has electric light rail, but it started out in 1881 with horse-drawn trams. These were followed by steam-powered trams before the whole system was electrified in 1897. There was also interurban service between Duisburg and Düsseldorf as early as 1899. That service continues today as Stadtbahn service.
The sender of this card was obviously a postcard and stamp collector, who purposely affixed the stamps on the picture side, and wrote "stamps on the other side" where the postage would normally go.
His message to Eugene Bloesch in San Francisco is also interesting:
Be so kind as to send me more postcards of the American army. If possible, please use Jamestown stamps affixed on the picture side.
With greetings from afar,
Duisburg on the Rhein
Kraut (?) Street 3328.2.08
The stamps that Johann refers to were issued in 1907 to commemorate the 300th anniversary of the Jamestown settlement in America. They looked like this: