Beethoven Piano Sonata No. 32, op. 111, 2nd movement
A couple of commenters have pointed out how Beethoven sounded like Scott Joplin playing ragtime about 75 years early for a few minutes in his last piano sonata, written in 1821-1822. This part (from 15:29 on) sounds like a good score for a Buster Keaton silent movie:
As far as I can tell, this is not a jazzed up arrangement. This is what Beethoven composed 195+ years ago.
In particular, the part from 1:00 to 1:08 is superb mid-20th Century American piano bar jazz.
I don’t really know what the implications of this are, other than that Beethoven and Chopin were titans.