"The Imperial City of Nuremberg (German: Reichsstadt Nürnberg) was a free imperial city — independent city-state — within the Holy Roman Empire. After Nuremberg gained piecemeal ...
independence from the Burgraviate of Nuremberg in the High Middle Ages and considerable territory from Bavaria in the Landshut War of Succession, it grew to become one of the largest and most important Imperial cities, the ´unofficial capital´ of the Empire, particularly because Imperial Diets (Reichstage) and courts met at Nuremberg Castle. The Diets of Nuremberg were an important part of the administrative structure of the Empire. The Golden Bull of 1356, issued by Emperor Charles IV (reigned 1346–78), named Nuremberg as the city where newly elected kings of Germany must hold their first Imperial Diet, making Nuremberg one of the three highest cities of the Empire." - (en.wikipedia.org 29.01.2020)