Duisburg is a city in the Ruhr metropolitan area of the western German state of North Rhine-Westphalia. Lying on the confluence of the Rhine and the Ruhr rivers in the center of the Rhine-Ruhr Region, Duisburg is the 5th largest city in North Rhine-Westphalia and the 15th-largest city in Germany. In the Middle Ages, it was a city-state and a member of the Hanseatic League, and later became a major centre of the iron, steel, and chemicals industries.