Johann Sebastian Bach was born on this date -- the calendar in effect at the time of his birth gave the date as March 31, but by today's calendar it was March 21 -- in 1685.
The clip above is of one of my favorite Bach pieces, the first movement, allegro, of Brandenburg Concerto No. 2 in F major, BWV 1047, by the Chamber Music Society of Lincoln Center. The musicians are identified on the video.