Because of a political compromise following German reunification, the German state maintains a substantial presence in Bonn, and the city is considered a second, unofficial, capital of the country. Bonn is the secondary seat of the President, the Chancellor, the Bundesrat and the primary seat of six federal government ministries and twenty federal authorities. The unique title of Federal City (German: Bundesstadt) reflects its important political status within Germany.
Founded in the 1st century BC as a Roman settlement, Bonn is one of Germany's oldest cities. From 1597 to 1794, Bonn was the capital of the Electorate of Cologne, and residence of the Archbishops and Prince-electors of Cologne. Composer Ludwig van Beethoven was born in Bonn in 1770. From 1949 to 1990, Bonn was the provisional capital of West Germany, and Germany's present constitution, the Basic Law, was declared in the city in 1949. From 1990 to 1999, Bonn served as the seat of government – but no longer capital – of reunited Germany.
The headquarters of Deutsche Post DHL and Deutsche Telekom, both DAX-listed corporations, are in Bonn. The city is home to the University of Bonn and a total of 20 United Nations institutions, including headquarters for Secretariat of the UN Framework Convention Climate Change (UNFCCC), the Secretariat of the UN Convention to Combat Desertification (UNCCD), and the UN Volunteers programme.
Situated in the southernmost part of the Rhine-Ruhr region, Germany's largest metropolitan area with over 11 million inhabitants, Bonn lies within the German state of North Rhine-Westphalia, close to the border with Rhineland-Palatinate. Spanning an area of more 141.2 km2 (55 sq mi) on both sides of the river Rhine, almost three quarters of the city lie on the river's left bank.
To the south and to the west, Bonn is bordering the Eifel region which encompasses the Rhineland Nature Park. To the north, Bonn borders the Cologne Lowland. Natural borders are constituted by the river Sieg to the north-east and by the Siebengebirge (also known as the Seven Hills) to the east. The largest extension of the city in north-south dimensions is 15 km (9 mi) and 12.5 km (8 mi) in west-east dimensions. The city borders have a total length of 61 km (38 mi). The geographical centre of Bonn is the Bundeskanzlerplatz (Chancellor Square) in Bonn-Gronau.
The German state of North Rhine-Westphalia is divided into five governmental districts (German: Regierungsbezirk), and Bonn is part of the governmental district of Cologne (German: Regierungsbezirk Köln). Within this governmental district, the city of Bonn is an urban district in its own right. The urban district of Bonn is then again divided into four administrative municipal districts (German: Stadtbezirk). These are Bonn, Bonn-Bad Godesberg, Bonn-Beuel and Bonn-Hardtberg. In 1969, the independent towns of Bad Godesberg and Beuel as well as several villages were incorporated into Bonn, resulting in a city more than twice as large as before.
Bonn has an oceanic climate (Cfb). In the south of the Cologne lowland in the Rhine valley, Bonn is in one of Germany's warmest regions.