The "less cleaning due to less coal" part is not something we really think much about these days, but the older limestone buildings can really show the difference. Here's a view with the old and either pressure-washed or redone wall: https://maps.app.goo.gl/Wso9gae4JPsN6NaG6 and that's on a residential side street... Imagine getting your clothes slowly covered with it every time you go out.