Rhine-Ruhr metropolitan region in the context of "Frankfurt"

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 Randstad (Dutch pronunciation: [ˈrɑntstɑt] ; "Rim City" or "Edge City") is a roughly crescent- or arc-shaped conurbation in the Netherlands, that includes almost half the country's population. With a central-western location, it connects and comprises the Netherlands' four biggest cities (Amsterdam, Rotterdam, The Hague, and Utrecht), their suburbs, and many towns in between, that all grew and merged into each other. Among other things, it includes the Port of Rotterdam (the world's busiest seaport outside Asia), the Port of Amsterdam (Europe's fourth-busiest seaport), and Amsterdam Airport Schiphol (Europe's fourth-busiest airport). With a population of approximately 8.4 million people it is one of the largest metropolitan regions in Europe, comparable in population size to the Rhine-Ruhr metropolitan region or the San Francisco Bay Area, and covers an area of approximately 11,372 km (4,391 sq mi). The Randstad had a gross regional domestic product of €510 billion in 2022, making it the second most productive region in the European Union, only behind the Paris metropolitan area. It encompasses both the Amsterdam metropolitan area and Rotterdam–The Hague metropolitan area. It is part of the larger Blue Banana megalopolis.

The Randstad's main cities are Almere, Amsterdam, Delft, Dordrecht, Haarlem, The Hague, Leiden, Rotterdam, and Utrecht. Other cities and towns include Alkmaar, Alphen aan den Rijn, Amersfoort, Amstelveen, Capelle aan den IJssel, Gouda, Heerhugowaard, Hilversum, Hoofddorp, Hoorn, Lelystad, Nieuwegein, Purmerend, Rijswijk, Schiedam, Spijkenisse, Vlaardingen, Zaandam, Zeist, and Zoetermeer.

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.

Cologne (/kə.ˈloʊn/ kə-LOHN; German: Köln [kœln] ; Kölsch: Kölle [ˈkœ̂lə] ) is the fourth-most populous city of Germany and the largest city of the German state of North Rhine-Westphalia with nearly 1.1 million inhabitants in the city proper and over 3.1 million people in the Cologne Bonn urban region. Cologne is also part of the Rhine-Ruhr metropolitan region, the second biggest metropolitan region by GDP in the European Union. Centered on the left bank of the Rhine, Cologne is located on the River Rhine (Lower Rhine), about 35 kilometres (22 mi) southeast of the North Rhine-Westphalia state capital Düsseldorf and 22 kilometres (14 mi) northwest of Bonn, the former capital of West Germany.

The city's medieval Cologne Cathedral (Kölner Dom) was the world's tallest building from 1880 to 1890 and is today the third-tallest church and tallest cathedral in the world. It was constructed to house the Shrine of the Three Kings and is a globally recognized landmark and one of the most visited sights and pilgrimage destinations in Europe. The cityscape is further shaped by the Twelve Romanesque churches of Cologne. Cologne is famous for Eau de Cologne, which has been produced in the city since 1709; "cologne" has since come to be a generic term.