Back in 1965 whilst taking Fine Arts at Goshen College with Professor Mary Oyer, I became fascinated by Petrushka by Igor Stravinsky. I had a vinyl recording of the orchestral version, and for the class, I undertook an analysis of the score. Later I heard a piano version and learned about the adaptation to piano. It is considered by many to be one of the most difficult pieces to play, and here is a clip of a portion of the piano version played by Yuja Wang:
Here is the complete multipart youtube compilation of the orchestra/ballet version. For me, one of the most intriguing parts of the score occurs precisely at 1:11 in Part IV - listen for the brass counter run - it repeats three more times and then the ensemble enlarges for the next four runs.