We all have our list of wishes, some of which might even be possible. One of mine is to be surprised by one of those flash crowds who appear and perform beautiful music. (I can't count how many times I've watched a couple of the Christmas ones.)
Via
gauroth,
here is Ravel's Bolero, a longtime favorite of mine, at a Scottish airport.
ETA:
Here is an even better one, in Copenhagen.
Looking at the faces of the listeners is as interesting as seeing the performers. The man at 1:52 seems to know the piece, he is so intent.