Fantasia

This without a doubt the greatest animated film in history. While highly acclaimed and well-known today, it was not terribly popular when it was first released. The idea of "Fantasia" is to take great pieces of music and draw animated sequences that match them. In doing so, it reverses the purpose of a movie's score; the movie serves and matches the music, not the other way around. This set up also means that there is no typical formula plot that is present in the vast majority of movies. In the first piece, the animation is vague and abstract, but in later ones it is of definite actions, objects, and stories. The two most famous(and my favorite) parts are probably "The Sorcerer's Apprentice" and "Rite of Spring". "Fantasia" is not only the best animated film ever made, but one of the greatest films period.