Castelfranco Veneto is a town and comune of Veneto, northern Italy, in the province of Treviso. It is the third largest municipality in the province …Castelfranco Veneto is a town and comune of Veneto, northern Italy, in the province of Treviso. It is the third largest municipality in the province by population after the capital Treviso and Conegliano. It is centrally located between the cities of Treviso, Padua and Vicenza, it is a walled city with a well-preserved medieval castle.