Returning to Florence in the year 1500, Leonardo was consulted in regard to the new bell tower of San Miniato, designed by Baccio d’Agnolo, and the static problems of the church of San Salvatore al Monte below it (the church called by Michelangelo «la bella villanella»).
In the Strozzi Papers in the Florence State Archive we can read the opinion of Leonardo, recorded after those of Jacopo del Pollaiolo, known as Cronaca, and Giuliano da Sangallo: «Lionardo da Vinci said what was wrong with San Salvadore. He has remedies for it, as he has shown in a drawing, in which can be seen the problems of the building and the water that penetrates among the layers of stones down to the bricks, and here in part the layers are cut, and that part of the building where the layers are cut, and are lacking, and he showed that the layers could be remade and cut and put back in place. And how to keep the sewers clean».
In the Codex Arundel, Leonardo had been concerned with the breakage of the walls and their repair. In regard to the lantern on the Milan Cathedral, he had already noted in the Codex Atlanticus the similarity between the physician and the architect in terms of "harmony of the elements". Leonardo considered buildings, in fact, to be living organisms having need, when "ill", of an "architect/physician". «Just as physicians, tutors, curers of the ill, must know what man is, what life is, what health is, and how the equality, the harmony of elements maintains them, and how discordance among them ruins and destroys them; and having a good knowledge of the aforesaid natures, can better provide a remedy than one who lacks such knowledge […]».
"Fatevi dare la difinitione e riparo del caso al Santo e all’altro e vedrete che omini son eletti per medici di malatie da lor non conosciute" (f. 147v, P82).