There have been settlements on the site of Châtel-Argent castle since prehistoric times and through the Roman Era. There is a chapel dedicated to Saint Columba of Sens which was built sometime between 1050 and 1070. The castle first appears in a document in 1176 as Castrum Argenteum. The castle was improved around 1275 under the direction of Count Peter II's architect James St. George and castle grew to the configuration we see today. This castle had always been owned by the counts and the dukes of Savoy.
The ruins can be accessed from Villaneuve by walking The Rampa, a staircase carved into the rock of the valley wall. The castle is located in the town of Villeneuve in the Aosta Valley region, at about 10 km west of the city of Aosta. The most prominent feature left in the ruins is its watchtower keep measuring just under 10 meters in diameter which overlooks the town below. The ruins themselves cover about 6,300 square meters. When the castle was whole, it was estimated to be able to hold 700 people in times of danger.
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.