I love stuff like this. You'll be walking along, just going for a coffee, and all of a sudden, there's beautiful live music right in front of you. Or, you're cycling home, and suddenly the stylings of an amateur pianist hit you as you pass under the bridge on the way home. Cambridge, being full of over-achieving students, has lots of people in the category of, "Oh, I don't play much anymore, but my parents made me take lessons so I'd get into _______ school." (Med, business, law, it doesn't matter.) They launch into Rachmaninoff, Beethoven, Mozart, you name it. It's a pretty fab city for a buncha pianos.
Here are some of the pianos:
(There's apparently a collaboration with Cambridge Ballerinas because there's a video on their website of a dude playing under Elizabeth Way bridge, and a girl dancing. It's 3:21 min, so you get a photo instead, but if you want to see it, it's on this page, about 2/3 of the way down.)
Silver Street Bridge
King's Parade, again
But this is probably the best one, close to our house in Arbury Court.