We attended this event last year and it was fun experience. I am including 2 links that talk about: "Not to be missed: the greatest night of in Paris is back on 2 October. Discover the wide range of (sculpture, video, installation, , etc.). Absolutely free!"
It takes place all night and is fun to roam around and check out.
For more info see:
The 1st link is English and the 2nd link also has a doc on the bottom of the page in English of the program.