Cologne is Germany's fourth-largest city (after Berlin, Hamburg, and Munich), and is the largest city both in the German Federal State ofNorth Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.

Cologne is located on both sides of the Rhine River. The city's famous Cologne Cathedral (Kölner Dom) is the seat of the Catholic Archbishop of Cologne. The University of Cologne (Universität zu Köln) is one of Europe's oldest and largest universities.

Bonn, officially the Federal City of Bonn, is a city on the banks of the Rhine River in the State of North Rhine-Westphalia, Germany. The city is the second official residence of the President of Germany, the Chancellor of Germany, the Bundesrat (upper house), and the first official seat of six German federal ministries and approximately 20 federal authorities. Bonn is located in the very south of the Rhine-Ruhr region, the largest metropolitan area of Germany. It is the seat of two major DAX-listed German corporations.