Map - Hagen (Kreisfreie Stadt Hagen)

Hagen is the 41st-largest city in Germany. The municipality is located in the state of North Rhine-Westphalia. It is located on the south eastern edge of the Ruhr area, 15 km south of Dortmund, where the rivers Lenne and Volme (met by the river Ennepe) meet the river Ruhr. As of 31 December 2010, the population was 188,529.

The city is home to the FernUniversität Hagen (University of Hagen), which is the only state-funded distance education university in Germany. Counting 69,982 students (winter semester 2022/23), it is Germany's second-largest university.

Hagen was first mentioned around the year 1200, and is presumed to have been the name of a farm at the confluence of the Volme and the Ennepe rivers. After the conquest of Burg Volmarstein in 1324, Hagen passed to the County of Mark. In 1614 it was awarded to the Margraviate of Brandenburg, according to the Treaty of Xanten. In 1701 it became part of the Kingdom of Prussia.

After the defeat of Prussia in the Fourth Coalition, Hagen was incorporated into the Grand Duchy of Berg from 1807–13. In 1815 it became part of the new Prussian Province of Westphalia.

The city developed more rapidly in the 19th century, stimulated by industrialization: the mining of coal and the production of steel in the Ruhr Area. In reaction to the Kapp Putsch in March 1920, when rightists tried to overthrow the elected government and restore the monarchy, tens of thousands of leftist workers in the Ruhr Valley, Germany's most important industrial area, rose up in protest. They were known as the Red Ruhr Army.

Thousands of workers went on strike and fought during the Ruhr Uprising, 13 March – 2 April 1920. Government and paramilitary forces were ordered against the workers, suppressing the uprising, and killing an estimated 1,000 workers. A memorial to the uprising was installed in Hagen.

By 1928, Hagen had developed into a city of more than 100,000 inhabitants.

During World War II, Hagen was bombed repeatedly, by both the Royal Air Force and the United States Eighth Air Force. On the night of 1 October 1943, 243 Lancasters and 8 Mosquitoes from the Royal Air Force's Bomber Command attacked the city. According to the Bomber Command Campaign Diary, "This raid was a complete success achieved on a completely cloud-covered target of small size, with only a moderate bomber effort and at trifling cost." Hagen sustained severe damage from that raid, and hundreds of civilians were killed.

After World War II, the city was included in the new state of North Rhine-Westphalia in the Federal Republic of Germany (FRG, also known as West Germany).