United Duchies of Jülich-Cleves-Berg
A market square sprang up on the banks of the Rhine and the square was protected by city walls on all four sides. In 1380, the dukes of Berg moved their seat to the town and Düsseldorf was made regional capital of the Duchy of Berg. During the following centuries several famous landmarks were built, including the Collegiate Church of St Lambertus. In 1609, the ducal line of the United Duchies of Jülich-Cleves-Berg died out, and after a virulent struggle over succession, Jülich and Berg fell to the Wittelsbach Counts of Palatinate-Neuburg, who made Düsseldorf their main domicile, even after they inherited the Electorate of the Palatinate, in 1685, becoming now Prince-electors as Electors Palatine.