Unless you have been in this very spot you may not guess, but this is from the platform of a Metro station. One generally thinks of Metro stations beneath ground but this is from the very large Bastille and this is a raised platform open to the water below, the Bassin de l'Arsenal or Canal St. Martin.

Last year I bought a book about the Metro in Paris and it has almost more than you ever wanted to know. It makes for good reading in and is a wonderful reference but I do wish that there was a picture-book of all the Metro stations inside and out.