The castrum in Castiglione delle Stiviere was founded probably in the 9th century, but it is much altered and restored, especially by the Gonzaga family of Mantua in the 16th century. The castle was home to a cadet branch of the House of Gonzaga, headed by the Marquis of Castiglione. Saint Aloysius Gonzaga (1568–1591) was born there as heir to the marquisate, but became a Jesuit. He died tending plague victims in Rome and was buried there, but his head was later translated to the basilica in Castiglione which bears his name.
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.