Enjoyed the museum near the waterfront with the archeological dig for Old Montreal underneath it. Also enjoyed Cirque du Soleil at the waterfront.

My two little boys loved the bug museum.

This gets asked a lot here. I l'm a creature of habit so I always hit Schwartz for smoked meat, Fairmont bagels (or st Viateur). I used to live on the Plateau, many good restaurants in that area.
Do a search also, this question comes up a lot.

Depends on interests...
We loved the art museum, Notre Dame Cathedral, Pointe-a-Calliere Archaeology/History museum, the Botanical Garden... While not fancy, the Redpath natural History museum has interesting fossils, if that'd be of interest to your family.

We also enjoyed the Biodome and Biosphere.

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Hi, I'm planning a 3 day trip to Montreal with tweens next month. Looking for recommendations - especially any food tours that you enjoyed? I'd also love restaurant recommendations. Other than planning to explore Old Montreal, Olympic Village/biodome, Mile End/Mt. Royal, let me know please if you had must see stops in town. Thanks!