Re: Strangely enough ...copyright complications
The photograph of the Plimpton tablet isn't "their stuff"; it's in the public domain.
Image copyright is horribly complicated. The maker of the image owns copyright in the image. If someone is permitted to take a photo of the image then they have copyright of the new image, but so (usually) does the original photographer!
Artworks are even more fun. If I own a picture by a modern artist, and take a photo of it, unless the artist has assigned all rights to me as part of the sale, I can't publish that photo (on the web or anywhere) without the permission of the artist (or other copyright holder).
So, does this tablet count as an original artwork? Although after 3700 years I suspect the carver's copyright has expired (depending on Babylonian copyright laws - are they in the Berne convention? After all, Disney characters are copyright for all time.)