Treasure paintings

These need to be fund in loot chests or hanged up in structures and can't be crafted kind of like discs. Structures where they could be found:
-Mansion: would have a large variety of illager themed paintings on the wall
-Pillager outpost: would rarely have art on one of the floors
-Nether fortress: would get the old wither painting
-Stronghold: would get paintings of most OW biomes, as hints to what there is to find
-Igloo basement: something to help player figure out how to get the zombie doctor achievement 

Master villagers would sell you a painting themed around there profession at the max level.
Wandering traders would also sometimes buy paintings if you have any extra.