On the site of the current Visconti-Castelbarco Castle, a fortification had been existing at least since the 10th century. At the end of the 13th century the castle became a property of the Visconti of Milan. It was then inherited by a lineage originated by Uberto, brother of Matteo Lord of Milan, initially the Visconti di Somma and later the Visconti di Cislago.
Destroyed in the 17th century, it was raised again in the form of a baroque villa on the original U-shaped plan and with two towers at the corners of the main facade. A crenellated roof was added to the building, providing the current revival castle aspect.
The castle belonged to the Visconti di Cislago until the 18th century. The marriage of the last female member of the Visconti di Cislago to a Castelbarco led the castle in the hands of the bridegroom's family. Their descendants assumed the surname of Castelbarco-Visconti.
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.