The Visconti Castle of Abbiategrasso lies on the axis of the Naviglio Grande canal and it was built to protect the waterway to Milan. In the 15th century it was one of the preferred places of residence of the dukes and duchesses of Milan.
The castle was probably built at the end of the 13th century on the site of a previous fortification (castro Margazario) near a Benedictine monastery. It was enlarged by Azzone Visconti (1329-1339) and Gian Galeazzo (1378-1402). In 1438 it was restored and embellished by the Duke Filippo Maria and – lost every defensive function and easily reachable by water along the Naviglio Grande – it became his favorite country mansion.
To the castle had some inclination the duchesses of Milan. Here had a stable residence Agnese del Maino, mistress of the Duke Filippo Maria and mother of Bianca Maria. The Sforza, dukes of Milan and descendants of Bianca Maria, favored the castle of Abbiategrasso to enhance their Visconti origins.
After the Visconti-Sforza period, the castle progressively assumed again the role of a stronghold, especially during the years of the Italian Wars (1494-1559). In 1658 three towers were demolished and the fourth was cut off. In 1862 it was sold to the municipality, which in the following years obliterated the ramparts to make place to the new train station, at the same time taking care of some restorations.
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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.