Duisburg in the context of "Mülheim"

The Ruhr (/ˈrʊər/ ROOR; German: Ruhrgebiet [ˈʁuːɐ̯ɡəˌbiːt] , also Ruhrpott German pronunciation: [ˈʁuːɐ̯pɔt] ), 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 1,160/km and a population of over 5 million (2017), it is the largest urban area in Germany and the third of the European Union. 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.

The Ruhr cities are, from west to east: Duisburg, Oberhausen, Bottrop, Mülheim an der Ruhr, Essen, Gelsenkirchen, Bochum, Herne, Witten, Hagen, Dortmund, Hamm and the districts of Wesel, Recklinghausen, Unna and Ennepe-Ruhr-Kreis. The most populous cities are Dortmund (with a population of approximately 612,065), Essen (about 583,000) and Duisburg (about 497,000).

The Rhine-Ruhr metropolitan region (German: Metropolregion Rhein-Ruhr) is the largest metropolitan region in Germany, with over ten million inhabitants. A polycentric conurbation with several major urban concentrations, the region covers an area of 7,110 square kilometres (2,750 sq mi), entirely within the federal state of North Rhine-Westphalia. The Rhine-Ruhr metropolitan region spreads from the Ruhr area (Dortmund-Bochum-Essen-Duisburg) in the north to the urban areas of the cities of Mönchengladbach, Düsseldorf (the state capital), Wuppertal, Leverkusen, Cologne (the region's largest and Germany's fourth largest city), and Bonn in the south. The location of the Rhine-Ruhr at the heart of the European Blue Banana makes it well connected to other major European cities and metropolitan areas such as the Randstad, the Flemish Diamond and the Frankfurt Rhine Main Region.

The metropolitan area is named after the Rhine and Ruhr rivers, which are the region's defining geographical features and historically its economic backbone.

Oberhausen (/ˈoʊbərhaʊzən/, German: [ˈoːbɐhaʊzn̩] ) is a city on the river Emscher in the Ruhr Area, Germany, located between Duisburg and Essen (c. 13 km or 8 mi). The city hosts the International Short Film Festival Oberhausen, The Static Roots Festival and its Gasometer Oberhausen is an anchor point of the European Route of Industrial Heritage.

Gelsenkirchen (/ˌɡɛlzənˈkɪərxən/, /ˈɡɛlzənkɪərxən/; German: [ˌɡɛlzn̩ˈkɪʁçn̩] ; Westphalian: Gelsenkiärken) is the 25th-most populous city of Germany and the 11th-most populous in the state of North Rhine-Westphalia with 262,528 (2016) inhabitants. On the Emscher River (a tributary of the Rhine), it lies at the centre of the Ruhr area, the largest urban area of Germany, of which it is the fifth-largest city after Dortmund, Essen, Duisburg and Bochum. The Ruhr is located in the Rhine-Ruhr metropolitan region, the second-biggest metropolitan region by GDP in the European Union. Gelsenkirchen is the fifth-largest city of Westphalia after Dortmund, Bochum, Bielefeld and Münster, and it is one of the southernmost cities in the Low German dialect area. The city is home to the football club Schalke 04, which is named after Gelsenkirchen-Schalke. The club's current stadium Veltins-Arena, however, is located in Gelsenkirchen-Erle [de].

Gelsenkirchen was first documented in 1150, but it remained a tiny village until the 19th century, when the Industrial Revolution led to the economic and population growth of the region. In 1840, when the mining of coal began, 6,000 inhabitants lived in Gelsenkirchen; by 1900 the population had increased to 138,000. In the early 20th century, Gelsenkirchen was the most important coalmining town in Europe. It was called the "city of a thousand fires" for the flames of mine gases flaring at night. In 1928, Gelsenkirchen was merged with the adjoining cities of Buer and Gelsenkirchen-Horst [de]. The city bore the name Gelsenkirchen-Buer, until it was renamed Gelsenkirchen in 1930. The city remained a center of coal mining and oil refining during the Nazi era, so was often a target of Allied bombing raids during World War II: nevertheless, over a third of the city's buildings date from before 1949. There are no longer coalmines in and around Gelsenkirchen; the city is searching for a new economic basis, having been afflicted for decades with one of the country's highest unemployment rates.

Bochum (/ˈboʊxʊm/, BOHKH-uum; US: /-əm/ -⁠əm; German: [ˈboːxʊm] ; Westphalian: Baukem) is a city in North Rhine-Westphalia. With a population of 372,348 (April 2023), it is the sixth-largest city (after Cologne, Düsseldorf, Dortmund, Essen and Duisburg) in North Rhine-Westphalia, the most populous German federal state, and the 16th-largest city in Germany. On the Ruhr Heights (Ruhrhöhen) hill chain, between the rivers Ruhr to the south and Emscher to the north (tributaries of the Rhine), it is the second largest city of Westphalia after Dortmund, and the fourth largest city of the Ruhr after Dortmund, Essen and Duisburg. It lies at the centre of the Ruhr, Germany's largest urban area, in the Rhine-Ruhr Metropolitan Region, the second biggest metropolitan region by GDP in the European Union, and belongs to the region of Arnsberg. There are nine institutions of higher education in the city, most notably the Ruhr University Bochum (Ruhr-Universität Bochum), one of the ten largest universities in Germany, and the Bochum University of Applied Sciences (Hochschule Bochum).

Wesel (German pronunciation: [ˈveːzl̩]) is a Kreis (district) in the northwestern part of North Rhine-Westphalia, Germany. Neighboring districts are Borken, Recklinghausen, district-free cities Bottrop, Oberhausen, Duisburg and Krefeld, districts Viersen, Cleves.