1. Bruno Walter worked closely with Gustav Mahler, whose music he helped to establish in the repertory, held major positions with the Leipzig Gewandhaus Orchestra, New York Philharmonic, Concertgebouw Orchestra, Salzburg Festival, Vienna State Opera, Bavarian State Opera, Staatsoper Unter den Linden and Deutsche Oper Berlin, among others, made recordings of historical and artistic significance, and is widely considered to be one of the great conductors of the 20th century.