Cologne became a Roman city in 50 A.D. In 310, Constantine built a bridge over the Rhine at the town, and in 785 it became the seat of an archbishop who was one of the seven Electors of the Holy Roman Empire, and ruled a large area as a secular lord in the Middle Ages. In 1288, however, he was defeated by Cologne's citizens and forced to move to Bonn. Cologne's location at the intersection of the Rhine with one of the major trade routes between the East and West was the basis of the town's growth. It was a member of the Hanseatic League, but officially became an Imperial Free City in 1475. In 1801, all the lands of the Holy Roman Empire on the left bank of the Rhine were incorporated into the French Republic. Thus, this region later became part of Napoleon's Empire, when Cologne lost its status as a free city. In 1815, at the Congr ess of Vienna, the city was made part of the kingdom of Prussia.

During the 19th and 20th Centuries, Cologne incorporated a number of surrounding towns, and by the time of World War I had grown to approximately 600,000 inhabitants. Industrialization changed the city and spurred its growth. Especially thriving branches were engine building and vehicle construction. By 1939, the population had risen to 772,221. Following an almost complete destruction during World War II, the German architect and urban planner Rudolf Schwarz undertook a major reconstruction of the town, creating many beautiful new thoroughfares.

In the 1980s and 1990s, Cologne's economy prospered due to two factors, steady growth in the number of media companies and the permanent improvement of the infrastructure, making Cologne one of the most easily accessible metropolitan areas in Europe. Today the economic and cultural capital of the Rhineland, Cologne has one of Europe's most vibrant and thriving art scenes. The city hosts over 30 museums and hundreds of galleries.

The city's most renowned landmark, however, is the world-famous Kölner Dom (Cologne Cathedral), seat to a Roman Catholic Archdiocese. The Cathedral, which began construction in 1248 but was abandoned around 1560, was eventually completed in 1880, not only as a religious building but also as a German national monument, celebrating the recently-founded German Empire and the continuity of the German nation since the Middle Ages. The Cathedral also claims to house the relics of the Three Magi.