It is in the post-scriptum that this ambassador says: "The Pope gave me to understand that the said Duchess [Lucrezia Borgia] will complete twenty-two years of age next April, and at that same time the Duke of Romagna will complete his twenty-sixth year."(1) 1 "Facendomi intendere the epsa Duchessa e di eta di anni ventidui, li quali finiranno a questo Aprile; in el qual tempo anche lo Illmo.

Duca di Romagna fornira anni ventisei." This certainly fixes the year of Cesare's birth as 1476; but we are to remember that Saraceni is speaking of something that the Pope had recently told him; exactly how recently does not transpire.

An error would easily be possible in so far as the age of Cesare is concerned.
In so far as the age of Lucrezia is concerned, an error is not only possible, but has actually been committed by Saraceni.

At least the age given in his letter is wrong by one year, as we know by a legal document drawn up in February of 1491--Lucrezia's contract of marriage with Don Juan Cherubin de Centelles.( 2) 2 A contract never executed.
According to this protocol in old Spanish, dated February 26, 1491, Lucrezia completed her twelfth year on April 19, 1491,( 3) which definitely and positively gives us the date of her birth as April 19, 1479.
3 "Item mes attenent que dita Dona Lucretia a XVIIII de Abril prop.
vinent entrara in edat de dotze anys." A quite extraordinary error is that made by Gregorovius when he says that Lucrezia Borgia was born on April 18, 1480, extraordinary considering that he made it apparently with this very protocol under his eyes, and cites it, in fact (Document IV in the Appendix to his Lucrezia Borgia) as his authority.
To return, however, to Cesare and Giovanni, there is yet another evidence quoted by Gregorovius in support of his contention that the latter was the elder and born in 1474; but it is of the same nature and of no more, nor less, value than those already mentioned.
Worthy of more consideration in view of their greater official and legal character are the Ossuna documents, given in the Supplement of the Appendix in Thuasne's edition of Burchard's Diary, namely: (a) October 1, 1480 .-- A Bull from Sixtus IV, already mentioned, dispensing Cesare from proving his legitimacy.

In this he is referred to as in his sixth year--"in sexto tuo aetatis anno." This, assuming Boccaccio's letter to be correct in the matter of April being the month of Cesare's birth, fixes the year of his birth as 1475.
(b) August 16, 1482 .-- A Bull of Sixtus IV, appointing Roderigo Borgia administrator of Cesare's benefices.