A large outdoor fountain display near the Place des Arts and Complexe Desjardins. The weather was a little cool when I visited to see kids running through the fountains during the daytime and at night the fountains are lit up. The surrounding streets are blocked off to traffic when events or festivals are held.
There was a film festival going on when I visited, so every night there was an outdoor movie theater set up. Definitely a great place to spend a warm summer evening.