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 characterized by having the warmest winters in Germany, especially its western part at the Lower Rhine area. Classified by Köppen-Geiger climate classification to be oceanic (Cfb). The area has four international commercial airports, and multiple smaller aerodromes for general aviation. North Rhine-Westphalia has the densest network of Autobahns in Germany. The rail, S-Bahn, U-Bahn and bus companies are administered through a consortium of local and regional transport lines, the "Verkehrsverbund Rhein-Ruhr". It offers a rapid transit system which interconnects all cities and their respective local buses, trams, U- and S-Bahn systems, partly under the umbrella of Deutsche Bahn. Their