you won't when the thick walls and all objects are radiating 30C heat at you
Most (not all) old euro cities don't get a good breeze unless they're built on the windward side of a hill because (generalizing here): the streets aren't a grid and everything is built to the same height.
plus the humidity is still there without aircon. 20C humid != 20C dry.
Doesn’t work when the overnight low is 20C