Public domain art is going to (along with custom art) play an important role in Leaves of Chiaroscuro. Since the game takes place in the Renaissance era, why not use art from the time period in the game? However, not only will the art be featured, so will the artists themselves. That means artists like Da Vinci and Botticelli will not only have their art featured, but they will also be characters in the game, with full writeups included!
The Public Domain directory I’m building will include sources of public domain art (though not all sources are 100% public domain, and it is important to check and make sure that a given piece actually is).
This directory has just started, and I’m hoping it will grow. If you know of a source of public domain art I should include please contact me.