An American academic is creating a searchable database of 12 million historic copyright-free images.
Kalev Leetaru has already uploaded 2.6 million pictures to Flickr, which are searchable thanks to tags that have been automatically added.
The photos and drawings are sourced from more than 600 million library book pages scanned in by the Internet Archive organisation.
The images have been difficult to access until now.
Mr Leetaru said digitisation projects had so far focused on words and ignored pictures.
"For all these years all the libraries have been digitising their books, but they have been putting them up as PDFs or text searchable works," he told the BBC.
They have been focusing on the books as a collection of words. This inverts that. Stretching half a millennia, it's amazing to see the total range of images and how the portrayals of things have changed over time.