The first attestation of works of fortification for the place called since the year 1000 "Monte Sighipertuli", "Montipertuli", or "Monte Spertuli", dates back to the end of the 11th century. A map from 1093 informs us, in fact, that the lord of the place, an exponent of the Ghisolfi family, was to have taken provisions in previous years to fortify a high point of his property, the castle of "Collepertuli". The deed was drawn up in Catignano, where Ildibrandino del fu Pagano of the Ghisolfi and Count Ughiccione, a member of the Cadolingi family, were present. One of the most interesting aspects of the document is that it brings to light the fact that the main protagonist, Count Ughiccione, had financially helped the Ghisolfi for the construction of certain masonry works and that the commitment was aimed, it would appear, toward realization of the fortifications of "Collepertuli". From this moment on, in fact, Montespertoli appears in the documents as a castle. A map from 1097of the monastery of Passignano, for example, mentions a castrum in a place called "montesipertuli". Subsequently, in 1134, we find some eminent characters drawing up a deed "in castro de montibertuli". These were the last exponents of that family branch of Ghisolfi still linked to the castle of Montespertoli, and who, nonetheless, do not appear to have descendants beyond the middle of the 12th century. During this century, in fact, the castle was part of the property of another noble family, that of the de Calebona, who also owned the nearby castle of Lucardo. This occurred probably due to the bond that had been created at the time of the construction of the castle of Montespertoli, between Ranieri di Ghisolfo of the Ghisolfi and Ghisla, daughter of Teuderico di Ildebrando, of the de Calebona family, (who was called, on one occasion, Teuderico "de Lucardo"). Thus, as the Ghisolfi branch was running out, the castle of Montespertoli passed into the hands of Teuderico da Lucardo’s descendants. During the 12th century the leading exponents of this branch of the family are mentioned in written sources as domini "de Montespertoli". Already by the beginning of the 13th century, however, this lineage of castle lords was henceforth resident in Florence, and known by the name of the eponymous castle, that is to say, the family of the "Da Montespertoli".