During the Middle Ages the city flourished as being located on one of the most important major trade routes between east and western Europe (including the Brabant Road, Via Regia and Publica).

Cologne was a free imperial city of the Holy Roman Empire and one of the major members of the trade union Hanseatic League.

The post-war rebuilding has resulted in a mixed cityscape, restoring most major historic landmarks like city gates and churches (31 of them being Romanesque).

In 716, Charles Martel commanded an army for the first time and suffered the only defeat of his life when Chilperic II, King of Neustria, invaded Austrasia and the city fell to him in the Battle of Cologne.

Charles fled to the Eifel mountains, rallied supporters and took the city back that same year after defeating Chilperic in the Battle of Amblève.

In 953, the archbishops of Cologne first gained noteworthy secular power when bishop Bruno was appointed as duke by his brother Otto I, King of Germany.

[15] In order to weaken the secular nobility, who threatened his power, Otto endowed Bruno and his archiepiscopal successors with the prerogatives of secular princes, thus establishing the Electorate of Cologne, formed by the temporal possessions of the archbishopric and included in the end a strip of territory along the left Bank of the Rhine east of Jülich, as well as the Duchy of Westphalia on the other side of the Rhine, beyond Berg and Mark.

[15] The economic structures of medieval and early modern Cologne were characterised by the city's status as a major harbour and transport hub on the Rhine.

According to the Treaty of Lunéville (1801) all the territories of the Holy Roman Empire on the left bank of the Rhine were officially incorporated into the French Republic (which had already occupied Cologne in 1794).

In 1837 the archbishop of Cologne, Clemens August von Droste-Vischering, was arrested and imprisoned for two years after a dispute over the legal status of marriages between Catholics and Protestants (Mischehenstreit).

These conflicts alienated the Catholic population from Berlin and contributed to a deeply felt anti-Prussian resentment, which was still significant after World War II, when the former mayor of Cologne, Konrad Adenauer, became the first West German chancellor.

Konrad Adenauer, the mayor of Cologne from 1917 until 1933 and later a West German chancellor, acknowledged the political impact of this approach, especially since Britain had opposed French demands for a permanent Allied occupation of the entire Rhineland.

This was an opportunity to create two green belts (Grüngürtel) around the city by converting the fortifications and their fields of fire into large public parks.

Cologne prospered during the Weimar Republic (1919–33), and progress was made especially in public governance, city planning, housing and social affairs.

Cologne was under the command of Lieutenant-General Freiherr Roeder von Diersburg, who was responsible for military operations in Bonn, Siegburg, Aachen, Jülich, Düren, and Monschau.

[34] Despite Cologne's status as the largest city in the region, nearby Düsseldorf was chosen as the political capital of the federated state of North Rhine-Westphalia.

The destruction of 95% of the city centre, including the famous Twelve Romanesque churches such as St. Gereon, Great St. Martin, St. Maria im Kapitol and several other monuments in World War II, meant a tremendous loss of cultural treasures.

The rebuilding of those churches and other landmarks such as the Gürzenich event hall was not undisputed among leading architects and art historians at that time, but in most cases, civil intention prevailed.

[43] A city agency (Stadtentwässerungsbetriebe Köln,[44] "Cologne Urban Drainage Operations") manages an extensive flood control system which includes both permanent and mobile flood walls, protection from rising waters for buildings close to the river banks, monitoring and forecasting systems, pumping stations and programmes to create or protect floodplains, and river embankments.

These dialects are spoken in the area covered by the Archdiocese and former Electorate of Cologne reaching from Neuss in the north to just south of Bonn, west to Düren and east to Olpe in the North-West of Germany.

The resulting web of relationships, with political, economic, and cultural links with each other in a system of mutual favours, obligations and dependencies, is called the 'Cologne coterie'.

[62] The most recent city council election was held on 13 September 2020, and the results were as follows: In the Landtag of North Rhine-Westphalia, Cologne is divided among seven constituencies.

Thus, the city centre today is characterized by modern architecture, with a few interspersed pre-war buildings which were reconstructed due to their historical importance.

Pigeons are the most often seen animals in Cologne, although the number of birds is augmented each year by a growing population of feral exotics, most visibly parrots such as the rose-ringed parakeet.

Of the twelve medieval city gates that once existed, only the Eigelsteintorburg at Ebertplatz, the Hahnentor at Rudolfplatz and the Severinstorburg at Chlodwigplatz still stand today.

Zülpicher Strasse and its surroundings, Neumarkt square, Heumarkt and all bars and pubs in the city are crowded with people in costumes dancing and drinking in the streets.

[77] In competition with Düsseldorf, the economy of Cologne is primarily based on insurance and media industries,[78] while the city is also an important cultural and research centre and home to a number of corporate headquarters.

Among the largest media companies based in Cologne are Westdeutscher Rundfunk, RTL Television (with subsidiaries), n-tv, Deutschlandradio, Brainpool TV and publishing houses like J. P. Bachem, Taschen, Tandem Verlag, and M. DuMont Schauberg.

Other large companies based in Cologne include the REWE Group, TÜV Rheinland, Deutz AG and a number of Kölsch breweries.

Roughly at the same time, a city centre bypass (Stadtautobahn) was planned, but only partially put into effect, due to opposition by environmental groups.