He wrote three symphonies and an opera "The Maid of Pskov", but in 1897 he stopped composing for several years. He spent his time inspecting naval bands and studied in great detail how musical instruments worked. Then, in 1880 he produced a new opera "May Night". It was performed in the Mariinsky Theatre. One of the main parts was sung by Fyodor Stravinsky, who was the father of Igor Stravinsky. Rimsky-Korsakov had by now become really interested in Russian folktunes and fairy tales. His next opera was "Snow Maiden". Then his friend Mussorgsky died, leaving lots of compositions unfinished. Rimsky-Korsakov spent a lot of time preparing them for publication. He made changes to some of Mussorgsky’s harmonies so that it suited his Romantic tastes. Nowadays many people think that Mussorgsky’s versions are better and that Rimsky-Korsakov had not understood properly what Mussorgsky had been trying to do. He also completed and orchestrated Borodin’s opera "Prince Igor" after Borodin died. He composed two very popular orchestral works: "Spanish Capriccio" (1887) and "Sheherazade" (1888). After this he hardly ever wrote any music which was just for orchestra, he concentrated instead on writing operas, e.g. The Tsar's Bride (1899).