A major Italian epic from the 1500s. You should absolutely read and reread this one.
This story weaves all of classical mythology, Arthurian romances, European Christendom, and even gets into pre-modern “sci-fi”. It’s a tour de force in Western Tradition, civilization, and culture - with heavy doses of comedy, tragedy, adventure, love, and war.
Gustave Dore drew over 200 illustrations for this story.
I recommend the Oxford World Classics translation.