Bochum is a city in North Rhine-Westphalia. With a population of 372,348, it is the sixth largest city, one of the most populous German federal states of North Rhine-Westphalia, and the 16th largest city of Germany. On the Ruhr Heights (Ruhrhöhen) hill chain, between the rivers Ruhr to the south and Emscher to the north, 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, and belongs to the region of Arnsberg. Bochum is the sixth largest and one of the southernmost cities in the Low German dialect area. There are nine institutions of higher education in the city, most notably the Ruhr University Bochum, one of the ten largest universities in Germany, and the Bochum University of Applied Sciences.

Dortmund is the third-largest city in North Rhine-Westphalia, after Cologne and Düsseldorf, and the ninth-largest city in Germany. With a population of 612,065 inhabitants, it is the largest city of the Ruhr as well as the largest city of Westphalia. It lies on the Emscher and Ruhr rivers in the Rhine-Ruhr Metropolitan Region, the second biggest metropolitan region by GDP in the European Union, and is considered the administrative, commercial, and cultural centre of the eastern Ruhr. Dortmund is the second-largest city in the Low German dialect area, after Hamburg.