Buildings at the site of Somma Lombardo Castle date from the 9th century and the fortress from the 13th century. In 1448, the brothers Francesco and Guido Visconti, took refuge in this town and castle from the forces of the Ambrosian Republic. They divided the landholdings and portions of the castle. The fortress has been amalgamated from adjacent residences, all once surrounded by a single moat. From the brother Francesco, who owned the newer portion of the castle, descend the Visconti di San Vito; while from Guido, who owned the lower and older portions of the castle, descend the Visconti di Modrone.
The San Vito castle contains frescoes attributed to the school of Camillo Procaccini and an altarpiece by Cerano. The castle also has an extensive collection of barber plates.
Parts of the castle are used for private events and open for guided tours.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.