The territory of Cortona is one of the richest artistic patrimonies connected to the ancient civilization in Central Italy. Recently, some remains of a Villanovan residence dating to the VIII century B.C. have been found. Furthermore, there are many evidences linked to the Etruscans.

Among them, some constructions and graves dating to all the Etruscan periods, from the archaic one to the Hellenic one, can be visited. The most ancient evidences of the Etruscan presence date to the VI century B.C. They are three burial mounds, one is set in Camucia, along the road to Chiusi, and the other two are near the Sodo.
Since that time, therefore, a rich and illustrious Etruscan aristocracy started to grow and transformed the centre into one of the most flourishing and important centres of the ancient League. In effect, also some walls protecting the town, that are visible still today with their 3-kilometre perimeter, were built in the IV century B.C.
In the Roman times, the city further increase its importance between the III and the I centuries B.C., when it received the status of a Roman city in the year 89. During this period, while the Etruscan-born families maintained their power, the territory was enriched with villas, such as the one of Ossaia. It was abandoned in the V century A.D., namely in the toughest period for a town like this that experienced the life of the Roman Empire after the year 0.
The information about Cortese in the Middle Ages does not clarify its role during the spread of Christianity. Despite the importance of the church of San Michele Arcangelo and of the Abbey of Farneta inherited from that time, it has not been possible to establish with certainty if Cortona was or not an Episcopal seat as many people think. Later, it was under the curia of Arezzo. From the XIII century on, the town was a free town and a podestà governed it. The town allied with Perugia to defend from Arezzo in the contest of the fights between Guelfs and Ghibellines.
The clash between Guelfs and Ghibellines characterized Cortona's XIII-century history. In 1232, the inhabitants of Cortone and the Florentines occupied the rival city. Nevertheless, Cortona was occupied and pillaged by the army of Arezzo that had been helped by the inhabitants of Arezzo themselves in 1258. Three years later, the Ghibellines of Cortona conquered the town again thanks to a new alliance, this time with Siena. In the XIV century, the Pope John XXII decided to give Cortona the status of Diocese since he understood that the town could not coexist with the bishopric of Arezzo. The town was given to the family of the Casali, who built their homonym palace here, until the beginning of the XV century.