The Cologne Lowland, also called the Cologne Bay or, less commonly, the Cologne Bight, is a densely populated area of Germany lying between the cities of Bonn, Aachen, and Düsseldorf/Neuss. It is situated in the southwest of the state of North Rhine-Westphalia and forms the natural southern conclusion of the Lower Rhenish lowlands and the transition to the Rhenish Massif.

Bonn is a federal city in the German state of North Rhine-Westphalia, located on the banks of the Rhine. It has a population of over 300,000. About 24 km (15 mi) south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ruhr region, Germany's largest metropolitan area and the second biggest metropolitan region by GDP in the European Union, with over 11 million inhabitants. It is a university city, was the birthplace of Ludwig van Beethoven and was the capital of West Germany from 1949 to 1990. Bonn was the seat of government of reunited Germany from 1990 to 1999.