The WDR Sinfonieorchester Köln exists since 1947. It has collaborated and recorded with renowned conductors such as Otto Klemperer, Sir Georg Solti, Dimitri Mitropoulos, Herbert von Karajan, and Claudio Abbado. Each season the orchestra performs about forty concerts in the Philharmonie and at the Westdeutscher Rundfunk, supplemented by concert tours in Europe and the Far East. In 1990–91 it performed all of Mahler’s symphonies with conductor Gary Bertini in Tokyo and Osaka. In addition to classical and Romantic repertoire it performs music of the twentieth and twenty-first centuries, including world and national premières of works by Hans Werner Henze, Mauricio Kagel, Luciano Berio, Luigi Nono, Bernd Alois Zimmermann, and Karlheinz Stockhausen. Since 1997–98 its principal conductor is Semyon Bychkov. It has recorded a number of CDs, including Richard Strauss, "Elektra"; Gustav Mahler’s symphonies; Karlheinz Stockhausen, "Gruppen"; Hans Werner Henze, "Tristan"; Bruno Maderna, oboe concertos; Bernd Alois Zimmermann, "Requiem für einen jungen Dichter"; Dmitry Shostakovich, orchestral lieder; Paul Hindemith, "Cardillac"; Carl Orff, "De temporum fine comoedia"; Helmut Lachenmann, "Ausklang" and "Nun"; York Höller, "Pensées" and "Der ewige Tag"; Peter Eötvös, "Atlantis" and "IMA"; Franco Donatoni, "In Cauda"; Gérard Grisey, "Les espaces acoustiques".