The Viscontean Castle of Trezzo on Adda riverwas built as a defensive fortification of a strategic bridge, of which today only a few remains remain visible.
The Castle of Trezzo The bridge was a single span of 72 meters, 25 meters high on the surface of the water. It was fortified and built on three levels to allow the separate passage of wagons and pedestrians. The shoulder is still visible on the Bergamo shore. The castle of Trezzo on Adda river was rebuilt on a Lombard stronghold commissioned by Queen Teodolinda. Surrounded on three sides by the river Adda, the castle was built in the fourteenth century at the behest of Bernabò Visconti. Due to its strategic position it was first disputed between Federico Barbarossa and the city of Milan. It was repeatedly destroyed or burned but always rebuilt. The current remains are those of the construction of Bernabò Visconti of which he was residence and then prison until his death (1385). After the conquest by Paolo Colleoni in 1404 and the subsequent destruction by Carmagnola, the Castle lost its importance.
In the nineteenth century, thanks to the material of which it was built, resistant and valuable, it ended up becoming a sort of quarry of stones to draw on. In fact the material was used for the construction of the Royal Villa of Monza and for the prisons of the Milanese Arena. Looking at the exteriors, one realizes how little remains of what must have been one of the most powerful castles in Lombardy. There are many legends and mysteries hidden in the ruins of this ancient manor. This is perhaps also due to the turbulent past of which he has repeatedly witnessed. It is said that the castle hides a great treasure, which belonged to Frederick Barbarossa, emperor of the Holy Roman Empire in the second half of the 12th century.
The basements, despite themselves, are the best preserved parts of the ancient manor. They appear as rough environments, in some stretches dug into the rock and so left, dark and wet. Here the prisoners, if they did not die otherwise, still had a survival undermined by environmental conditions. Some rooms have been worked and adapted to be used as stables or kitchens.
In the basement of the castle there is then the room of the drop. A terrible torture to which the prisoners bound under one of these drops were subjected. These falling slowly from the ceiling, they dug his skull causing him an atrocious death. In the basement there is a door that leads nowhere. However, it is believed that this road led to the depths of the earth and then to another castle some tens of kilometers away, even passing under the bed of the river Adda. In the Middle Ages in fact these underground passages that linked the castles to each other were common. Useful in case of siege, to escape without passing through the main door. Some think that right in these galleries, now closed by time, Barbarossa may have hidden his treasure.