With a population of 588,250 residents as of the year 2021, Dortmund is the third-largest city in the state of North Rhine-Westphalia after Cologne and Düsseldorf, and it is the eighth-largest city in all of Germany. It is the biggest city in Westphalia and the largest city in the Ruhr, which is the largest metropolitan region in Germany with around 5.1 million residents. The Ruhr is also the largest urban area in Germany. It is located in the Rhine-Ruhr Metropolitan Region, on the Emscher and Ruhr rivers (both of which are tributaries of the Rhine), and it is the administrative, economic, and cultural heart of the eastern Ruhr. The Rhine and the Ruhr rivers are both located in Germany. After the city of Hamburg, Dortmund is the second-largest city in the region that uses the Low German dialect.
Around the same time it was established, 882, Dortmund was designated an Imperial Free City. It was the "head city" of the Rhine, Westphalia, and the Netherlands Circle of the Hanseatic League throughout the 13th and 14th century. This title was held by the city for the whole of those two centuries. The city was completely wiped out during the War of the Thirty Years and did not regain its former status until the beginning of the Industrial Revolution. After thereafter, the city developed into a significant hub for the coal, steel, and beer industries in Germany. As a direct consequence of this, Dortmund was one of the cities in Germany that was bombarded the most during World War II. The catastrophic bombing strikes that took place on March 12, 1945, destroyed 98% of the buildings in the central business district of the city. The record for the most bombing aircraft directed at a single target in World War II was set by these bombing operations, which included almost 1,110 aircraft.
After the collapse of its century-long steel and coal industries, the area has adjusted and moved its focus to high-technology biomedical technology, micro systems technology, as well as services. This transformation has occurred while the industries have been in decline. In the Innovation Cities Index that was released by 2thinknow, Dortmund was categorised as a Node city. It was also listed in the top twelve innovation cities in the European Union. Furthermore, Dortmund is the most environmentally friendly and technologically advanced city in Germany. Other important industries include retail trade, tourist economies driven by leisure and entertainment, creative industries, and logistics. Dortmund is an important transport junction due to its central station and airport, which is the third-busiest airport in North Rhine-Westphalia. This is especially true for the surrounding Ruhr area as well as Europe (the countries of the Benelux), and due to the fact that it has the largest canal port in Europe, it also has a connection to important seaports on the North Sea.
Dortmund is home to a wide variety of educational and cultural institutions, such as the Technical University of Dortmund and Dortmund University of Applied Sciences and Arts, as well as the International School of Management and other educational, cultural, and administrative facilities with over 49,000 students. Additionally, Dortmund is home to a large number of museums, such as the Museum Ostwall, Museum of Art and Cultural History, and German Football Museum, as well as numerous theatres and music venues, such as the Konzerthaus or the Opera House of Dortmund. Nearly half of the region that makes up the municipality is made up of canals, wooded areas, agricultural land, and open green spaces including expansive parks like Westfalenpark and Rombergpark. This stands in sharp contrast to the almost a century's worth of massive coal mining and steel mills that took place in the previous century. It is fair to say that Borussia Dortmund is one of the most successful football clubs in Germany.