Today's "Antico Frantoio" of Saguato Stefano is a large building with strong walls, a roof of four guards. It is on four floors above ground and probably hides underground dungeons. In the past it was a strong house. It was erected in the late Middle Ages on a previous building of which only the foundations remain, now buried under the torrent S. Pietro.
Documents attest that in 1537 it housed a few friars partly preserved with a legacy of a friar of the Castello di Diano. Later it became property of the convent of Santa Caterina in Genova. In the sixteenth century the fort-house was used as a defense outpost of the Church of St. Peter, in the case of barbarian raids. At the beginning of the seventeenth century it was rented and annually gave the friars fifteen large barrels of "good, clear and marketable" oil. Also the mill and the oil mill, existing inside the building, were rented at the value of three barrels of oil per year.
Around the middle of the eighteenth century, during the war of secession, the fort-house was used as a barracks, first of Franco-Spanish troops then of Austrian and Piedmontese troops. Peace returns, in 1754, the complex was still granted in rents to the citizens of Diano S. Pietro. Between 1797 and 1805 it served as a barracks for Austrian troops and formations of the National Guard of the Ligurian Republic. After the Napoleonic period, starting from 1805 it was always an oil working center, passing several times of ownership.