The best of Canada's <150,000 cities is probably Saint John, NB (pop. 126,000). As one of the oldest and historically largest cities that has since stagnated, it has an oversized 19th century urban core that's quite charming & densely built:
https://goo.gl/maps/QVknWzxWJ24dVYpD8
https://goo.gl/maps/7FRn7iL6fuSu8Wrc9
https://goo.gl/maps/y5FSVLTLWy7zgdEc6
https://goo.gl/maps/uaKbCRGfRoHyTkat8
