Run by Steve Bartrick, who advertises it as ‘a free image resource for historians, genealogists and anyone undertaking family history, ancestry or local history research.’
There are 31,100 images (as of July 2014) of old and antique prints, maps and portraits, dating from the 17th century but mostly from the later 18th century and 19th century. The images are all of prints and maps that are for sale on his main website, antiqueprints.com but include all those that are no longer visible on his commercial site (because they have been sold).
Copyright for non-commercial is free. Steve is happy for those running personal websites dealing with family history, genealogy, or other historical research as well as charities and non-profits to use the images in return for a link back to his website or a credit such as ‘Image courtesy of ancestryimages.com’.
For commercial use, you need to contact him directly to discuss terms.