The north wing was begun in 1687, ready by 1752, and furnished in succeeding years. Work on the wing extending away from the river was begun during the reigns of Johann Friedrich Karl von Ostein (1743–1763) and Friedrich Karl Josef von Erthal (1774–1802). Erthal was the last Prince-Elector of the old electorate. His successor Karl Theodor von Dalberg was both Archbishop-Elector of Mainz and Arch-Chancellor of the remaining Empire on the right bank of the Rhine. Due to the resolutions of the "Reichsdeputationshauptschluss" his seat was moved to Regensburg, which became the new seat of the archbishopric.