History of the Ruhr and steel industries have declined drastically History of the Ruhr The actual boundaries of the Ruhr vary slightly depending on the source, but a good working definition is to define the Lippe and Ruhr as its northern and southern boundaries respectively, the Rhine as its western boundary, and the town of Hamm as the eastern limit. In the Middle Ages, local power was vested primarily in the counts ("Grafen") of Berg, Mark and Cleves. The left bank of the Rhine was held by the Archbishop of Cologne. The Hellweg was an important trade route crossing the region from Duisburg to
Rhine-Ruhr is the University of Cologne "(Universität zu Köln)", founded in 1388 AD. Other universities include: The following register lists all municipalities that officially belong to Rhine-Ruhr area. Demographically, these municipalities include 20 cities (German: ), each with more than 100,000 inhabitants, and 11 districts (German: ), each with a population of more than 250,000 inhabitants. Some districts only belong partly to Rhine-Ruhr area. In such a case only the municipalities that belong to the metro area are listed. Rhine-Ruhr The Rhine-Ruhr metropolitan region () is the largest metropolitan region in Germany with over 10 million inhabitants. It is of polycentric