Not sure where to put this but I'm sure many people here would be interested. It's basically a collection of free historical artistic works, 60,000 pieces and growing. You can use these any way you want, they are CC0 license, meaning usable for commercial renders, no attribution needed. Which is nice because I am often looking for ways to add background filler, artwork, posters, etc to my scenes. So you can use these any way you wish.

https://www.nga.gov/artworks/free-images-and-open-access

just search here for whatever you want:

https://www.nga.gov/artwork-search?download=1

everything with a download button is public domain.