Hello fellow flâneur! Though you won’t get the same level of safety, I definitely recommend Paris as a destination to walk around. The city feels like a museum and you can end up finding all sort of random monuments and beautiful architecture along the way. Also some cool street art. Obviously use common sense and you’ll be fine.

PS: I did Tokyo quite a lot, Shanghai too, though you usually need to take the metro at some point. San Francisco is also great if you don’t mind the hills (and also use common sense).