Click here to go to the list of images of unidentified mills - currently 1072 results. As in the screenshot above, you'll see the 'place/mill' filters on the left - you can use these to narrow down the images shown. For instance, clicking 'England' will limit it just to pictures of unidentified mills in England (like this). You can then further filter by selecting counties in England. A filtered term will appear underlined - click it again to remove the filter. Just avoid clicking the term 'unidentified mill' itself, or you'll remove that filter and see every image in the catalogue.
If you come across any you know, or which shouldn't be in the list (e.g. not real mills; mills already identified) send an email to firstname.lastname@example.org and we'll update the catalogue.