Mussorgsky is famous for his operas and songs. He discovered new ways of writing for the voice which were very tuneful but which also suited the Russian language. His most famous opera is "Boris Godunov". He wrote an overture called "Night on a Bare Mountain". Another very famous piece is called "Pictures at an Exhibition". He wrote it for the piano, but many years after his death another composer called Maurice Ravel orchestrated it and this is the version people usually hear today. Some of his works were re-orchestrated and "improved" by the composer Nikolai Rimsky-Korsakov. In recent years people have started to think that what Mussorgsky wrote originally was better.