Imperial Free City in the context of "Margrave"

Dortmund (German: [ˈdɔʁtmʊnt] ; Westphalian: Düörpm [ˈdyːœɐ̯pm̩]; Latin: Tremonia) is the third-largest city in North Rhine-Westphalia, after Cologne and Düsseldorf, and the ninth-largest city in Germany. With a population of 614,495 inhabitants, it is the largest city (by area and population) of the Ruhr as well as the largest city of Westphalia. It lies on the Emscher and Ruhr rivers (tributaries of the Rhine) in the Rhine-Ruhr Metropolitan Region, the second biggest metropolitan region by GDP in the European Union, and is considered the administrative, commercial, and cultural centre of the eastern Ruhr. Dortmund is the second-largest city in the Low German dialect area, after Hamburg.

Founded around 882, Dortmund became an Imperial Free City. Throughout the 13th to 14th centuries, it was the "chief city" of the Rhine, Westphalia, and the Netherlands Circle of the Hanseatic League. During the Thirty Years' War, the city was destroyed and decreased in significance until the onset of industrialisation. The city then became one of Germany's most important coal, steel, and beer centres; as a consequence, it was one of the most heavily bombed cities in Germany during World War II. The devastating bombing raids of 12 March 1945 destroyed 98% of the buildings in the inner city. Involving more than 1,110 aircraft, the raids were the largest targeting a single city during World War II. Today, around 30% of the city’s buildings date from before the war.

The Diet of Worms of 1521 (German: Reichstag zu Worms [ˈʁaɪçstaːk tsuː ˈvɔʁms]) was an imperial diet (a formal deliberative assembly) of the Holy Roman Empire called by Emperor Charles V and conducted in the Imperial Free City of Worms. Martin Luther was summoned to the diet in order to renounce or reaffirm his views in response to a Papal bull of Pope Leo X. In answer to questioning, he defended the views that had been criticized and refused to recant them. At the end of the diet, the Emperor issued the Edict of Worms (Wormser Edikt), a decree which condemned Luther as "a notorious heretic" and banned citizens of the Empire from propagating his ideas. Although the Reformation is usually considered to have begun in 1517, this edict is the first overt schism associated with it.

The diet was conducted from 28 January to 25 May 1521 at the Bischofshof palace in Worms, with the Emperor presiding. Other imperial diets took place at Worms in the years 829, 926, 1076, 1122, 1495, and 1545, but unless plainly qualified, the term "Diet of Worms" usually refers to the assembly of 1521.

Frankfurt was a major city of the Holy Roman Empire, being the seat of imperial elections since 885 and the city for imperial coronations from 1562 (previously in Free Imperial City of Aachen) until 1792. Frankfurt was declared an Imperial Free City (Freie und Reichsstadt) in 1372, making the city an entity of Imperial immediacy, meaning immediately subordinate to the Holy Roman Emperor and not to a regional ruler or a local nobleman.

Due to its imperial significance, Frankfurt survived mediatisation in 1803. Following the collapse of the Holy Roman Empire in 1806, Frankfurt fell to the rule of Napoleon I, who granted the city to Karl Theodor Anton Maria von Dalberg; the city became known as the Principality of Frankfurt. The Catholic cleric Dalberg emancipated Catholics living with the city boundary. In 1810 Dalberg merged Frankfurt with the Principality of Aschaffenburg, the County of Wetzlar, Fulda, and Hanau to form the Grand Duchy of Frankfurt. After the defeat of Napoleon and the collapse of the Confederation of the Rhine, Frankfurt was returned to its pre-Napoleonic constitution via the Congress of Vienna of 1815 and became a sovereign city-state and a member of the German Confederation.