Cave paintings are illustrations or pictographs drawn on the walls of a cavern system. Most commonly cave paintings depict animals of the surrounding region. In fictional worlds they can be used to age a world or explore a fictional history. Cave paintings may pertain to an ancient prophecy or ancient civilization.
When designing cave paintings for a fictional world, consider the people who made these illustrations and what was most important for them culturally. Cave paintings may have survived through many eras, and graffiti, dust, and other debris may obscure the paintings or portions of them.