Some of the things I saw as I walked:
(My sad attempt at capturing myself on the Promenade. Let's be honest--this picture could have been taken anywhere. But I had to try.)
The Jardin de Reuilly park. A total hidden gem. (Well, not totally hidden, as you can see. But not packed by any means.)
If you visit Paris and have an hour or two that you'd like to escape the city for a while, this is definitely worth your time. I enjoyed it a lot, and I decided I wouldn't mind living in that area--it seemed pretty cool.
To access the promane plantee, take the Metro to Bastille, and you'll find the promenade plantee behind the opera building.