During the Middle Ages, Brunswick was an important center of trade, one of the economic and political centers in Northern Europe and a member of the Hanseatic League from the 13th century to the middle of the 17th century. By the year 1600, Brunswick was the seventh largest city in Germany. Although formally one of the residences of the rulers of the Duchy of Brunswick-Lüneburg, a constituent state of the Holy Roman Empire, Brunswick was "de facto" ruled independently by a powerful class of patricians and the guilds throughout much of the Late Middle Ages and the Early modern period. Because of the growing power of Brunswick's burghers, the Princes of Brunswick-Wolfenbüttel, who ruled over one of the subdivisions of Brunswick-Lüneburg, finally moved their "Residenz" out of the city and to the nearby town of Wolfenbüttel in 1432. The Princes of Brunswick-Wolfenbüttel didn't regain control over the city until the late 17th century, when Rudolph Augustus, Duke of Brunswick-Lüneburg, took the city by siege. In the 18th century Brunswick was not only a political, but also a cultural centre. Influenced by the philosophy of the Enlightenment, dukes like Anthony Ulrich and Charles I became patrons of the arts and sciences. In 1745 Charles I founded the "Collegium Carolinum", predecessor of the Brunswick University of a Technology, and in 1753 he moved the ducal residence back to Brunswick. With this he attracted poets and thinkers such as Lessing, Leisewitz, and Jakob Mauvillon to his court and the city. "Emilia Galotti" by Lessing and Goethe's "Faust" were performed for the first time in Brunswick.