The origin of the name Cosona dates back to the Etruscans (Cusna, kusunias), the first recorded inhabitants of the area.
The oldest written document belongs to the Carolingian era (828) in which Cosona is mentioned as a hamlet and a castle. In the Middle Ages Cosona belonged to the powerful Sienese family ‘Tolomei’ who had conspired against the Republic of Siena and consequently were subjected to the destruction of the castle (1393).
The parish church, Santa Maria in Cosona, situated along the road which connected the Via Francigena (toward Rome) to the Via Laurentana (toward Loreto) was disputed by the bishops of Siena and Arezzo.
In 1465 Niccolo’ Forteguerri, native of Pistoia and related to Pope Pius II, bought the castle, which in the meantime had been rebuilt as a fortress, from King Ferdinand of Aragona: it has since then belonged to the same family, today Bichi Ruspoli Forteguerri.
The master building (house) was restored to its present state at the beginning of the 1900s by the Sienese architect Arturo Viligiardi.
Until the 1970s the farm was based on the old sharecropping system and was the center of a community of about 300 inhabitants. It included a school and a parish church dedicated to the Sts Laurentino and Pergentino. It was famous for its dancing celebrations which attracted people from the surrounding area.
In 1996 partial views of Cosona were made famous by the film “The English Patient” by Anthony Minghella, winner of 9 Oscars.