Ruhr (river) in the context of "Duisburg"

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.

The Lippe (German pronunciation: [ˈlɪpə] ) is a river in North Rhine-Westphalia, Germany. It is a right tributary of the Rhine and 220.3 km (136.9 mi) in length with an elevation difference of 125 metres and a catchment area of 4.890 km².The source is located at the edge of the Teutoburg Forest in Bad Lippspringe close to the city of Paderborn. It runs westward through Paderborn, Lippstadt and then along the northern edge of the Ruhr area, parallel to the river Emscher and river Ruhr. The river finally enters the Rhine at Wesel.

Mülheim, officially Mülheim an der Ruhr (German pronunciation: [ˈmyːlhaɪm ʔan deːɐ̯ ˈʁuːɐ̯] , lit. 'Mülheim on the Ruhr'; Low German: Mölm; Kölsch: Müllem) and also described as "City on the River", is a city in North Rhine-Westphalia in western Germany. It is located in the Ruhr Area between Duisburg, Essen, Oberhausen and Ratingen. It is home to many companies, and two Max Planck Institutes.

Mülheim an der Ruhr was granted city rights in 1808, and a century later its population surpassed 100,000, officially making it a major city.”

Essen (German pronunciation: [ˈɛsn̩] ) is the central and, after Dortmund, second-largest city of the Ruhr, the largest urban area in Germany. Its population of 574,082 makes it the fourth-largest city of North Rhine-Westphalia after Cologne, Düsseldorf and Dortmund, as well as the tenth-largest city of Germany. Essen lies in the larger Rhine-Ruhr metropolitan region, second largest by GDP in the EU, and is part of the cultural area of Rhineland. Due to its central location in the Ruhr, Essen is often regarded as the Ruhr's "secret capital".

Two rivers flow through the city: the Emscher in the north, and in the south the Ruhr River, which is dammed in Essen to form the Lake Baldeney [de] and Lake Kettwig [de] reservoirs. The central and northern boroughs of Essen historically belong to the Low German Westphalian dialects area, and the south of the city to the Low Franconian Bergish area.

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).

Hagen (German pronunciation: [ˈhaːɡn̩] ) is a city in the state of North Rhine-Westphalia, in western Germany, on the southeastern edge of the Ruhr area, 15 km south of Dortmund, where the rivers Lenne and Volme meet the Ruhr. In 2023, the population was 197,677.

The city is home to the FernUniversität Hagen (University of Hagen), the only state-funded distance education university in Germany.