[Sailor on ship] - Glass negative photogrpah. Public domain.
Picryl description: Public domain image of an artillery gun, or cannon, free to use, no copyright restrictions.
A very large dataset of various big guns, howitzers, mortars, columbiads, all types of canon-like things - everything besides machine guns and rockets. This collection as well as all massive collections on Picryl.com required two steps: First, we picked a set to train AI vision to recognize cannon artillery, and after that, ran all 25M+ images in our database through our image recognition network. All media in the collection is in the public domain. There is no limitation on the dataset usage - educational, scientific, or commercial.