Here is a great resource for primary sources! The Louvre Museum has uploaded almost half a million of their collection to this website complete with documentation.
https://collections.louvre.fr/en/
Great for primary source analysis.
Yes! I am grateful that with nearly 500,000 objects available, they made some thematic albums, as well as a search function. Half a million art objects not enough? The Museum Computer Network has made a handy-dandy guide to help you find more images freely available from museums around the world: https://mcn.edu/a-guide-to-virtual-museum-resources/