 In 1560 Francis Laparelli was called to Rome by Pope Pius IV, at the request of his cousin Serbelloni, with the task of restoring the fortifications of Civitavecchia.In the same year he designed fortifications to defend the new mouth of the Tiber, and in 1561 directed the defense works at Vatican Hill.In 1565 he completed the great bastioned pentagon of the Castel Sant'Angelo, made progress on the defenses of the Vatican, collaborated with Michelangelo Buonarroti on work on the great dome of St. Peter's Basilica and wrote on the stability of the dome.