Hagen
Possibly best known as the home of the Fern Uni, Deutschland's equivalent to the Open University.
Wuppertal
Wuppertal is the location of the famous Schwebebahn, or monorail, which primarily runs along the river
It was the home town of Friedrich Engels. A museum to Engels can be found on Friedrich Engels Strasse.
Xanten
Posibly the only German town to have a name beginning with the letter 'X'. It was a former Roman legionary center.