Castelfranco born in 1195 when the town of Treviso, recently formed, felt the need to build a fortress on the border with rival Padua and Vicenza, in an area where the river was the only Muson ephemeral natural demarcation. The site chosen was also in a strategic position: a pre-existing embankment on the east bank of the river, near the confluence of the streets and Aurelia Postojna and centrally located between the forts and stately Castle Godego Treville and bishops of Salvatronda, Riese and Resana.

Something quite special, the people of the castle had not been trained as soldiers, but by free citizens, which he established, could be exempt from all taxation (hence the name Castelfranco, ie "free"). However, the interiors were not organized in a typical urban layout: there was a real

square and the most important buildings were distributed along the main road or even backward, as the case of the church, the accounting office and the infirmary.

The castle was ruled by two consuls, hold office for six months. In addition to normal administrative duties were to manage the justice in the name of the mayor of Treviso. Each console must be accountable to partner and work against him if he broke the law.

The castle passed in 1246 to Ezzelino III da Romano, who fortified it further with two rounds and a tower on the south (Padova), returned to Treviso September 27, 1259, the day of death of the "Tyrant".

Castelfranco in 1329 went to Can Grande della Scala, lord of Verona.

Within these walls was born in 1478 the great painter Giorgione.