St Peter’s basilica was still a demolition site when Bramante passed away in 1514. The architect had had been relieved from his duties the year before when his patron Pope Julius died. Since then, the project had passed through a number of hands: Raphael, Fra Giocondo and Baldassare Peruzzi. However, it was the powerful Florentine family of architects and engineers, da Sangallo, which would finally be entrusted with the future development of the project.
In fact, the pope’s chief architect had originally been a member of the family. At the time that Bramante’s project was chosen, Giuliano da Sangallo had been so confident of winning the commission that he prematurely moved his entire family to Rome. He was called back a decade later in 1514, but only lived long enough to see 18 months on the job.
However, as Raphael died in 1520 at the age of 37 and as Peruzzi eventually fell off after the sack of Rome in 1527, his nephew Antonio da Sangallo the younger gradually became the new capo maestro.
In 1539, Pope Paul III commissioned a wood model, which can still be seen in the Vatican Museum today. It shows the direction of Sangallo’s ideas and also sums up many of the turnabouts in the project, which had occurred over the last three decades since the original inception. For instance, whether to choose a Greek or a Latin cross plan was a point every new architect seemed destined to reverse.
Sangallo produced something of a hybrid, though its outward appearance is clearly directional. With the dominant front towers, the facade appears more like a classical take on a gothic cathedral than an Italian basilica. The choice, however, is not too surprising as the northern solution gives back the sense of monumental scale, which may have been lost by making the dome recede from the west front.
On all sides of the structure da Sangallo placed a series of arches between engaged columns supporting an entablature, a concept that had been used in on modern buildings in modified form by Bramante and Alberti, but which is ultimately derived from the Coliseum or Theatre Marcellus. The round ambulatory structure at the transepts shows the debt to this source most clearly.
As such, especially when contrasted with the later amendments by Michelangelo, da Sangallo appears as a late high renaissance rather than mannerist artist. At the same time as Michelangelo was developing the double order, da Sangallo stuck with a more orthodox formula. The same contrast can be seen in the Farnese palace, which was also later modified by Michelangelo. As projected by da Sangallo, the building would have been a classically conscious and correct rendition of a Florentine palazzo. Subtly though it appears, Michelangelo turned to contrast where da Sangallo sought regularity and harmony.
Despite this, Sangallo’s St. Peter’s appears cluttered in style and structurally complex. Ironically, it was Michelangelo’s project, with gigantic double order pilasters, which gave the structure, what in hindsight seems to qualify as the most convincingly classical solution.
Antonio da Sangallo the younger died in Florence in 1546 and the project passed to a reluctant Michelangelo.