 On 1 January 1547 in the reign of Pope Paul III, Michelangelo, then in his seventies, succeeded Sangallo the Younger as "Capomaestro", the superintendent of the building program at St Peter's.He is to be regarded as the principal designer of a large part of the building as it stands today, and as bringing the construction to a point where it could be carried through.He did not take on the job with pleasure; it was forced upon him by Pope Paul, frustrated at the death of his chosen candidate, Giulio Romano and the refusal of Jacopo Sansovino to leave Venice.