The description of the bas-reliefs in
Purgatorio canto X (the bas-reliefs are by God the Artist!) are a good example of ekphrastic writing.
Luca Signorelli’s monochromes in the Orvieto cathedral depict scenes from Dante, including
images of the bas-reliefs--visual art based on ekphrastic poetry that is based on imaginary works of art (no doubt a composite of ones Dante actually saw).
How's that for complicated?