History of Cologne (Cologne Tower), one of Cologne's most prominent highrises. Secondly, a permanent improvement in traffic infrastructure, which makes Cologne one of the most easily accessible metropolitan areas in Central Europe. Due to the economic success of the Cologne Trade Fair, the city arranged a large extension to the fair site in 2005. The original buildings, which date back to the 1920s, are rented out to RTL, Germany's largest private broadcaster, as their new corporate headquarters. A controversy started after Muslims in Cologne sought to build a mosque. Most important for the history of Cologne since the Middle Ages is the Cologne
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