Nikolaus Harnoncourt is an Austrian conductor, particularly known for his historically informed performances of music from the Classical era and earlier. Starting out as a classical cellist, he founded his own period instrument ensemble in the 1950s, and became a pioneer of the Early Music movement. Around 1970, Harnoncourt started to conduct opera and concert performances, soon leading renowned international symphony orchestras, and appearing at leading concert halls, operatic venues and festivals. His repertoire has since widened to include composers of the 19th and 20th century. In 2001 and 2003, he conducted the Vienna New Year's Concert. Harnoncourt is also the author of several books, mostly on subjects of performance history and musical aesthetics.