Two of his best-known works, the Pietà and David, were sculpted before the age of thirty. Despite his low opinion of painting, Michelangelo also created two of the most influential frescoes in the history of Western art: the scenes from Genesis on the ceiling of the Sistine Chapel in Rome, and The Last Judgment on its altar wall. As an architect, Michelangelo pioneered the Mannerist style at the Laurentian Library. At the age of 74, he succeeded Antonio da Sangallo the Younger as the architect of St. Peters Basilica. Michelangelo transformed the plan,with the western end being finished to his design, and the dome being completed after his death, with some modification.