'Galileo di Vincentio Ghalilei fiorentino e di m.a Giulia sua donna fu batezato a di’ 19 ditto Compari e Chavalieri forno el S.re Pompeo et Messer Haverardo de’ Medici in Chapella di S.to Andrea'. So reads the baptism act of Galileo Galilei preserved in the archive of the Primaziale of Pisa, dated 19 February 1564. We are in front of Casa Ammannati, the home of the maternal family of the great Pisan genius. Giulia Ammannati was born in Villa Basilica in 1538, but soon moved to Pisa due to her father's activity as a timber merchant, Cosimo Ventura of the Ammannati of Pescia. She had three sisters Diamante, Dorotea and Ermellina, and a brother, Leone. It was the latter who accompanied Giulia to the altar, her father having passed away, when on 5 July 1562 she married Vincenzo Galilei, here in Pisa, guaranteeing a dowry of 100 gold scudi that was used by the newlyweds for food during a whole year: dote scutorum centum aurum et pannis et lanis […] expenses victus pro tempore unius annis. The mystery of the three native houses: Until 1800, it was thought that Galileo was born in the parish of Sant'Andrea in Kinzica, or in Fortezza, near today’s Giardino Scotto. This thesis was refuted since to have the mandatory requirement to be born in the Fortezza his father, Vincenzo Galilei, needed to be a master of arms, but we know well that he was a merchant and luthier. The second birthplace is located in Borgo Stretto, casa Bocca, at the corner with via Mercanti. This was the home that Vincenzo rented a few months before the great scientist's birth and where he lived with Giulia for about ten years. The baptism certificate mentions the parish, Sant'Andrea, while the aforementioned house belongs to that of San Michele in Borgo. From the notarial archives it was discovered that the home of the Ammannati was in via Giusti and it is very likely that, respecting the customs of the time, Giulia had returned right there to give birth to her firstborn, helped during the birth by her mother Lucrezia and her sisters. Galileo was therefore born in this house on 15February 1564 and was baptised in the nearby Church of Sant'Andrea Foris Porta (from the house it is possible to see the back of the church), four days later, on the 19th, in the presence of the Knight of Santo Stefano Jacopo Forno da Modena (Chavalieri oven el S.re Pompeo) and Averardo De ‘ Medici.
Curious fact: Galileo was not baptised on the day of his birth, as is customary, since, given his neonatal asphyxia, it was necessary to wait for an insufflation treatment that saved him from suffocation.