It wasn't only The Cathedral, but most of Paris ! It was Malraux (Minister of Culture at that time) who brought up laws for every buildings to be cleaned up ! The Marais district was so black, dark and shabby looking with it's narrow streets, that my wife as a child didn't like to visit some family who lived there. It was spooky !
Yep, I'm old enough to remember that, such as the slums where now stands the Pompidou center ! When I was a student, the statistics showed that there was one shower for thirty flats... Since we have had a bathroom boom
That cleaning spur has aggravated all those limestones, getting off the thin calcite protection made by time, air and pollution, rendering those stones very vulnerable to rain and sudden icing. Those "cleaning" works took more then a dozen years on Notre Dame, because of the variety of stone used (several origins), some of those crumbling in sand when cleaned (usually high pressure water with sand). Since then I've always seen scaffolding or works on different parts of the Cathedral, changing stone parts...!
It's quite incredible to realize that in a 30 to 60 years span, an old city can be so changed that most people who lived those changes, have almost forgotten all about them.
For the pictures, H.Cartier-Bresson, Boubat, Lartigue, Dosineau have all recorded those times
