Barenboim played the piano in Vienna and Rome in 1952 , Paris in 1955 , London in 1956 . In 1957 he played in New York with Leopold Stokowski conducting . Barenboim made his debut as a pianist in Vienna and Rome in 1952 , Paris in 1955 , London in 1956 , and New York in 1957 under the baton of Leopold Stokowski .