Mühlbacher Klause (Chiusa di Rio Pusteria) castle was built by Sigmund, Duke of Tyrol, between 1458 and the 1480's. It replaced an older fort, built in the 13th century and which was situated about 600 meters west of the present location.
Both fortifications were built here to control the passage through the Pusteria valley which was the border between the counties of Gorizia and Tyrol.
In the 18th century an administration wing, once annexed to the residential building, was destroyed by a flood. Around 1871 the northeastern tower was partly destroyed.
The most recent wartime involvement of the castle dates from the so-called French War at the beginning of the 19th century, when Napoleon's troops were faced by the Tyrolese militia.
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.