This is a good piece on how, actually, Medieval Cathedrals Used to Be Full of Brilliant Colors. If you imagine them to be dark and dreary and colourless, read the piece. They were likely nothing like that, based on some good detective work by restoration specialists.
You can see many more pictures of it here, at Colossal.
Quite a few things, according to this: www.theatlantic.com/ideas/archive/2018/11/what-should-america-do-its-empty-church-buildings/576592/
if you have a church in your neighbourhood, there is a good chance one of the things mentioned in the article will happen in the next 10 years.