Are these cities doable with a 18 month old baby in a stroller? or are the streets more like cobblestone?

I used to live in Montreal with a toddler. Yeah, there are cobblestones in Old Montreal, but it still is easier than carrying the kid.

We had a lightweight stroller, so whent he going got too rough, we folder the stroller and put the boy up on my shoulders.

And most of the city has normal sidewalks and raods, and inside stores and malls (and the tunnels under the city) are satisfactorily smooth.

BAK

BAK

There are only cobblestone streets in Old Montreal (a very small area compared to the rest of the city). The rest of the city is stroller-friendly. You should be fine on the sidewalks both in Montreal and Quebec City.