Dedicate your fourth day to exploring the art and culture of Naples. Start with a visit to the National Archaeological Museum, home to an impressive collection of Roman artifacts, including the Farnese Hercules and the Pompeii mosaics. Next, head to the Capodimonte Museum, housed in a former royal palace, and admire its vast collection of Renaissance and Baroque art. Don't miss the opportunity to visit the Naples Cathedral, a stunning example of Gothic architecture, and the nearby San Gregorio Armeno, a street famous for its artisan workshops and nativity scene displays.