I was surprised to learn that there is a spectacular waterfall (~30m higher than Niagara Falls) only a few minutes drive from the old city. We had a nice afternoon walking around the park. There's even a bridge so you can walk overtop of the falls.
If you've ever driven between Montreal and Quebec, you've probably noticed the strange restaurant/hotel surrounded by piles of dinosaurs and trucks. Needless to say, it's always a big hit with Julien.