I don’t know if this falls into the genre, but what about the original Dante’s Inferno? The big one with the amazing Gustav Dore woodcuts. It’s a very entertaining read in spite of the Shakespearian prose. Funny in some parts, obscene in others, very imaginative. And the Gustave Dore woodcuts are delightfully gruesome.
I've seen it argued the The Divine Comedy is the first science fiction proto-novel.