Writers' Guild Forums - for URU Agebuilders using the Open-Source Plasma plug-in

Don't always like Adobe anymore.
But they do put out a monthly bunch of articles that are pretty good sometimes.

Here's a good list of resources for free images from Nat'l Archives, museums, and so on:
https://create.adobe.com/2019/2/15/free_...m_mus.html
and an earlier list here:
https://create.adobe.com/2018/1/8/not_an...e_ima.html

Some good textures in there, reference material, inspiration. Especially good when you want wall art for framing.

Unsplash has an amazing selection of really high quality images.
I have not yet figured out why they're free!
And if you want some Myst-style inspiration, here's one from their collection.
credit: John Fowler