Castello Visconteo was built in 1300, commissioned by Bernabò Visconti, beside a fortress which is said to have been built under Queen Teodolinda. This fortification has seen turbulent times, vicious struggles and defeats at the hands of Barbarossa, the Torrianis and the Viscontis. It was here that Bernabò was actually killed by his nephew Gian Galeazzo. All that remains today of the imposing castle is the square tower which is 42 metres high, the well which was built in 1400 under the chatelain Vercellino, and the underground passages. The shoulder and the joint foundation are still visible of the bridge which was built over the Adda in the same period and used for thirty years before being destroyed by Carmagnola in 1416. Since 1982 the Castle has been owned by the Town Hall of Trezzo. Visitors can see the Sala Bernabò hall and, in the Villa del Castello, there is a Didiactic Information Space has been with photos of the archaeological finds from the Lombard era and a perfect reconstruction of what is known as the “giant’s tomb”.