The big bands sponsored by the various state-run radio stations became one of the pillars of jazz in postwar Germany, even though they mostly played swing, dance, and entertainment music. Additionally, the spread of jazz was aided by the jazz clubs that sprang up around American military barracks. In addition to providing entertainment for American troops, they also facilitated a kind of cultural exchange between German and American musicians. Likewise, jazz clubs (often called “Hot Clubs” or, somewhat later, “Jazz Keller,” since they were located in arched cellars), began opening in large West German cities such as Düsseldorf, Hamburg, Hanover, and Stuttgart. Both professional and amateur jazz musicians had a chance to play in these clubs. Whereas the professionals came to prefer the technically and intellectually more challenging modern jazz (that is, bebop and cool jazz), many young people and amateurs preferred the New Orleans or Dixieland style, which was more accessible and easier to play.