I was going to nominate Modest Mussorgsky’s "Pictures At An Exhibition", but during a little research learned that though the work became very popular and often performed after orchestrations were written for it in the early 1900’s, most famously by Maurice Ravel in 1922, Mussorgsky’s original piano transcription was written in 1874, and published in 1886, five years after the composer’s death. I love the work, both as performed on solo piano, and with full orchestration.