Bonn (German pronunciation: [bɔn] ) is a federal city in the German state of North Rhine-Westphalia, located on the banks of the Rhine. With a population exceeding 300,000, it lies about 24 km (15 mi) south-southeast of Cologne, in the southernmost part of the Rhine-Ruhr region. This metropolitan area, Germany's largest, is also the second largest in the European Union by GDP, with over 11 million residents.

Cologne is the largest city of Germany's most populous federal state of North Rhine-Westphalia, and its 1 million+ (2016) inhabitants make it the fourth most populous city in Germany after Berlin, Hamburg, and Munich. The largest city on the Rhine, it is also the most populous city both of the Rhine-Ruhr Metropolitan Region, which is Germany's largest and one of Europe's major metropolitan areas, and of the Rhineland. Centred on the left bank of the Rhine, Cologne is about 45 kilometres (28 mi) southeast of North Rhine-Westphalia's capital of Düsseldorf and 25 kilometres (16 mi) northwest of Bonn. It is the largest city in the Central Franconian and Ripuarian dialect areas.

The city's famous Cologne Cathedral (Kölner Dom) is the seat of the Catholic Archbishop of Cologne. There are many institutions of higher education in the city, most notably the University of Cologne (Universität zu Köln), one of Europe's oldest and largest universities, the Technical University of Cologne (Technische Hochschule Köln), Germany's largest university of applied sciences, and the German Sport University Cologne (Deutsche Sporthochschule Köln), Germany's only sport university. Cologne Bonn Airport (Flughafen Köln/Bonn) is Germany's seventh-largest airport and lies in the southeast of the city. The main airport for the Rhine-Ruhr region is Düsseldorf Airport.