Among the many versions of Saint Peter and also the many designers who took part in the big factory, it was decided to model Saint Peter, designed by Antonio da Sangallo the Young, for two main reasons: first, more practical, is the quantity and quality of the sources that characterize the San Pietro of Sangallo. The drawings of Antonio Labacco, one of his follower, along with the large wooden model stored in one of the octagonal drum of the actual Basilica, are in fact a unique example compared to the rest of the material linked to the other cathedral’s versions we are aware of.

The second reason – not less important - concerns the “renewed interest” and the peculiar  architectural quality of the Sangallo’s project.

The peculiarity of the main body is configured in its final mixed figuration: as a centric-longitudinal “organism”. Ambitious attempt to synthesize two architectural types – the centric one, refered to the first project by Bramante, and the second one, the longitudinal, carried on by Bramante himself along with Raphael. Types, that had been setted alternatively in the attempt to solve the difficult problem of the architectural and cultural connection between the new St. Peter’s church and the former Basilica, memory of the Apostle’s grave.