Minecraft wiki entry for Item_Frame, associated text: Item frames can be placed on the sides of cactus blocks, pressure plates, fences, trees, slabs, cobblestone walls, chests, doors, and all solid blocks. They can also be placed on the top and bottom of these blocks. To place on chests and doors, the player needs to be sneaking. As item frames are an entity, multiple item frames can occupy the same block, although on different faces. It also allows non-solid blocks to occupy the same space.‌[Java Edition only]