Google Art Project has quite a lot images, but they use some tiling tool to let you zoom on a super-large image. Some people have "pirated" them and uploaded them here: https://commons.wikimedia.org/wiki/Category:Gigapixel_images...

There are also various scripts around to re-create the image locally, but the first I tried was broken.

I have a few of those (and the Dutch museum) loaded cycling up on my Electric Objects display.