Actually, there are many orchestrations of Mussorgsky's Pictures at an Exhibition, which he wrote as a series of piano sketches. Ravel's is the best known, and is most often played. It was famous for being one of the first orchestral pieces to use a new instrument of the era, the saxophone, as a solo instrument in the section Il Vecchio Castello, (The Ancient Castle). This was the version I grew up hearing, specifically Fritz Reiner's recording with the Chicago Symphony. I got really weirded out in college when a friend put another recording on, and it was ALL WRONG! Turned out that it was Leopold Stokowski conducting his own orchestration of the same piano original, using completely different instruments and arrangements. It's funny how a particular arrangement or even specific recording of a musical piece that you hear first becomes the "right" version somehow in your brain.

In program notes for a concert featuring the Ravel arrangement, I found the following passage:

Mussorgsky's Pictures at an Exhibition remained relatively obscure until 1923, when Ravel completed an orchestration of the suite for Serge Koussevitsky. Ravel's scoring was not the first attempt to transform Pictures into an orchestral piece, nor was it the last--there have been at least a dozen arrangements of Pictures, beginning with an orchestration by Mikhail Tushmalov in 1891, and orchestral versions by Sir Henry Wood, Ravel, Leonidas Leonardi, Leopold Stokowski, Lucien Caillet, Walter Goehr, and Sergei Gorchakov. There have also been scorings for other groupings of instruments, including Elgar Howarth's brass ensemble version, a guitar version by Yamashita, Tomita's electronic scoring, and even a fancifully-staged version by the rock band Emerson, Lake, and Palmer. Ravel's masterful orchestration is better known than any other, including Mussorgsky's own piano suite!

We recently got a CD re-release of the piano piece being played by the great Russian pianist Sviatoslav Richter, and it's wonderful in the original scoring, too!