When the Cardinal was made to leave Bologna in 1428 Dufay went to Rome to work for the pope. He became a member of the Papal Choir. In 1434 he was made "maistre de chappelle" in Savoy. He seems to have left Rome when the papal choir had money problems. Yet in 1435 he was again in the service of the papal chapel, but this time it was in Florence. In 1436 Dufay composed the festive motet "Nuper rosarum flores", one of his most famous compositions, which was sung at the dedication of Brunelleschi's dome of the cathedral in Florence.