Districts of Cologne within city limits), while 174,87 km² (43.2 percent) lie right of the Rhine. In regard to population, Cologne is the largest city in the state of North Rhine-Westphalia and the fourth largest city in Germany. Since the city's foundation in 38 BC, Cologne grew through numerous extensions and incorporation of surrounding municipalities. Since the construction of the Medieval wall in 1180, the area of the old imperial city of Cologne has not changed for more than 600 years and was only extended over the old city walls in 1794, just short before the arrival of French troops and Cologne's incorporation
Cologne leading galleries for postwar and contemporary art. Several orchestras are active in the city, among them the Gürzenich Orchestra, which is also the orchestra of the Cologne Opera and the WDR Symphony Orchestra Cologne ("German State Radio Orchestra"), both based at the Cologne Philharmonic Orchestra Building (Kölner Philharmonie). Other orchestras are the Musica Antiqua Köln and the WDR Rundfunkorchester Köln, and several choirs, including the WDR Rundfunkchor Köln. Cologne was also an important hotbed for electronic music in the 1950s (Studio für elektronische Musik, Karlheinz Stockhausen) and again from the 1990s onward. The public radio and TV station WDR was