In Rome, he saw Michelangelo's ceiling fresco for the Sistine Chapel, as well as works by the extremely Mannerist artist Parmagianino he of the famous "Madonna of the Long Neck" (and the adult-proportioned baby Jesus on her lap).
WSJ: Il Rosso Fiorentino | Deposition | A Maelstrom of Grief | Masterpiece by Peter Plagens