system was approved at the end of the Thirty Years' War in the Peace of Westphalia (1648) which named four "Paritetic Imperial Cities" (): Augsburg, Biberach, Dinkelsbühl and Ravensburg. In 1803 the Immerwährende Reichstag passed the Reichsdeputationshauptschluss, a bill which included the secularisation and mediatisation of many German states — the first meaning the confiscation of the estates belonging to the church, the second the incorporation of the imperial estates and Imperial Free Cities into larger regional states. As a result, Ravensburg first became a Bavarian exclave within Württemberg. After a swap of estates between Bavaria and Württemberg it was incorporated in the Kingdom of Württemberg in 1810. Since Ravensburg was impoverished and depopulated after the Thirty Years' War, only a few new buildings were raised during the 18th and the early 19th century. The benefit of this economic stagnation was the conservation of a widely intact medieval city with nearly all towers and gates of the historic fortification. 20th century During World War II Ravensburg was strategically of no relevance. Ravensburg did not harbor any noteworthy arms industry (unlike nearby Friedrichshafen with its large aircraft industry), but was home to a major aid supplies center belonging to the Swiss Red Cross. The historic city centre was not damaged by air raids. By 1945, the city came into the French occupation zone and thus came in 1947 to the newly founded state of Württemberg-Hohenzollern, which in 1952 merged to the state of Baden-Württemberg. In the 1970s, Ravensburg increased in population and territory by the incorporation of smaller communities like Eschach, Schmalegg and Taldorf. Ravensburg University of Cooperative Education was established in the city in 1978. In the 1980s, the Old Town was renovated and all transit traffic was banned from the city centre. Economy and infrastructure Ravensburg is a thriving shopping city in the wealthy region of Upper Swabia. Unemployment is relatively low. The nearest large cities are Munich, Stuttgart and Zurich, approximately a two-hour drive away each. Ulm, Konstanz and Bregenz are each less than a one-hour drive away. Ravensburg is part of an urban agglomeration that also comprises Weingarten (Württemberg) and several suburbs. Ravensburg, Weingarten, and Friedrichshafen (on the shores of Lake Constance) share the functionality of a Oberzentrum (that is, the highest-ranked centre in the system of spatial planning and development in Baden-Württemberg). Transport Ravensburg is located at a crossing of the federal roads (national highways) B30,