In December of 2013, the British Library released over one million pictures from books spanning the 17th to 19th century and shared them on Flickr Commons. The images were scanned and digitized entirely by software, however numerous volunteers later tagged and sorted the images into groups to make them usable. You can find the results here.
Most of the images appear to be maps, however there are also illustrations, photos, sheet music, and even decorative papers. The swan shown on this post comes from a book of children’s songs published in 1896. I added a colored background, and it will make a nice stamp at some point. Hopefully you will find something interesting here to explore!