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.

The Ruhr, also referred to as the Ruhr area, sometimes Ruhr district, Ruhr region, or Ruhr valley, is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km2 and a population of over 5 million (2017), it is the largest urban area in Germany. It consists of several large cities bordered by the rivers Ruhr to the south, Rhine to the west, and Lippe to the north. In the southwest it borders the Bergisches Land. It is considered part of the larger Rhine-Ruhr metropolitan region of more than 10 million people, which is the third largest in Western Europe, behind only London and Paris.