The only element left of the ancient complex of defensive walls and castle, erected by the Visconti between 1325 and 1357, also survived the demolition in 1809. The Tower is a four-sided building on the river, used as a prison until the second half of the 18th century. The architectural structure of the prison cells recalls an oven, from here we understand the famous name “forni” (ovens).
The first to test them was actually their commissioner Galeazzo Visconti, imprisoned for nine months with his brothers and children by his former ally, the emperor Ludwig the Bavarian. Still visible on the tower are the slits for the drawbridge, a gothic mullioned window and a stone coat-of-arms of Charles II of Spain.