On October 28, 1467 in a deed notarized by Ser Piero, we read: «actum Florentie in Populo Sancti Appolinaris, in domo habitationis mei notarii infrascripti», that is, compiled by Ser Piero at his own residence in Sant’Apollinare.
This was already, very probably, the house in which Ser Piero lived until 1480, in the Popolo di Sant’Apollinare, in Via delle Prestanze (also known as Via del Montecomune, or as Sdrucciolo della Dogana), enlarged in the 19th century by the implementation of Poggi's projects for Florence as capital of Italy, and forming the present-day Via dei Gondi. The building belonged to the Arte dei Mercatanti (or Calimala). Ser Piero had sublet it from Michele di Giorgio del Maestro Cristofano and then from Giuliano Gondi. In fact Ser Piero, in the Land Office report of 1480, specified: «I first stayed in a house owned by the Arte de’ Mercatanti […] rented for 30 florins a year. I engage to pay that rental fee to Giuliano Gondi up through next October, 1480».
In 1485 Gondi, who already owned the adjoining house, in which he lived, also bought the houses owned by the Arte dei Mercatanti. He had these buildings demolished and commissioned Giuliano da Sangallo to build the present-day Palazzo Gondi. Work stated on July 29, 1490. Here an inscription recalls: «LEONARDO DA VINCI / LIVED HIS AUSPICIOUS YOUTH / IN A HOUSE OWNED BY THE ARTE DEI MERCATANTI / THAT WAS BOUGHT AND DEMOLISHED BY GIULIANO GONDI / TO BUILD THIS PALACE / AT THE COMPLETION OF WHICH IN MDCCCLXXIV / THE COMMUNE AND THE OWNER BY COMMON ACCORD / DESIRED TO PRESERVE THE MEMORY OF SUCH A NAME / ON THIS FINE AND NOBLE BUILDING / TO ENHANCE ITS DECORUM».
It is interesting to note that Leonardo mentions in the Codex Atlanticus (f. 1024v), among his other friends, Giuliano Gondi, who was engaged in many commercial activities outside of Florence; his sons, in fact, worked in Naples, in Hungary and in Constantinople.