Today I learned there exists a version of Pictures at an Exhibition by Modest Mussorgsky arranged for an accordion:
Of course, Pictures at an Exhibition is originally a piano piece (all the orchestral versions you might be familiar with are arrangements by composers other than Mussorgsky) so arranging it for a different individual instrument it relatively easy.
Actually, while I'm at it, here's a performance of Pictures at an Exhibition on piano, based on Mussorgsky's original score. Almost all versions you hear are based on translitterations with mistakes in them (and/or omit entire parts of the piece. Maurice Ravel's orchestration, which is probably the most famous version, does both), whereas this is probably the closest version to Mussorgsky's original intention.