Red Mars Digital
From a 2013 post on the British Library's Digital Scholarship blog, I learned that they had recently uploaded over a million images scanned from 17th, 18th and 19th century books into the public domain.
The files were not curated, were largely unlabelled and were listed in no particular order, so the collection wasn't straightforward to work with - but as there were no end of fascinating forgotten artworks buried in there I decided to recombine some of them into a new piece for myself.
The process of collecting suitable source images, cutting the subjects from their backgrounds and assembling the collage (using GIMP) took up my spare evenings for about a month - but I now have a large, unique finished piece hanging on my wall that I'm pretty happy with. So it was worth it!
You can explore the finished artwork closer-up here:
The final framed piece, displayed on my living room wall: