Cologne (Koln, Keulen, Koeln) is the largest city in the German federal State of North Rhine-Westphalia and the fourth-largest city in Germany (after Berlin, Hamburg, and Munich). It is located within the Rhine-Ruhr metropolitan region, one of the major European metropolitan areas, and with more than ten million inhabitants, the largest in Germany.
Cologne is located on both sides of the Rhine River, less than eighty kilometres from Belgium. 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.
During the 19th and 20th centuries, Cologne absorbed numerous surrounding towns, and by World War I had already grown to 700,000 inhabitants. Industrialisation changed the city and spurred its growth. Vehicle and engine manufacturing were especially successful, though heavy industry was less ubiquitous than in the Ruhr area. The cathedral, started in 1248 but abandoned around 1560, was eventually finished in 1880 not just as a place of worship but also as a German national monument celebrating the newly founded German empire and the continuity of the German nation since the Middle Ages. Some of this urban growth occurred at the expense of the city's historic heritage with much being demolished (for example, the city walls or the area around the cathedral) and sometimes replaced by contemporary buildings.
Cologne was designated as one of the Fortresses of the German Confederation. It was turned into a heavily armed fortress (opposing the French and Belgian fortresses of Verdun and Liège) with two fortified belts surrounding the city, the remains of which can be seen to this day. The military demands on what became Germany's largest fortress presented a significant obstacle to urban development, with forts, bunkers, and wide defensive dugouts completely encircling the city and preventing expansion; this resulted in a very densely built-up area within the city itself.
1904. City of Cologne.
1904. Fire brigade. City of Cologne