Altensteig Castle probably dates back to the 12th century. In 1287, the castle was first mentioned as being owned by the Counts of Hohenberg. Hermann, son of Margrave Rudolf of Baden, conquered the town but had to return it to Count Burkhard von Hohenberg in 1288. In 1398, the Hohenbergers sold the Lordship of Altensteig to the Margraves of Baden. The castle became the seat of the Baden bailiffs.
In 1603, as part of a territorial exchange, Altensteig came under the rule of the Duchy of Württemberg. From 1605, Heinrich Schickhardt built the New Castle as the administrative and residential seat of the Württemberg bailiffs. The old castle served as a grain silo from the 18th century onwards. The lower part of the striking residential tower, with a floor area of about 11 meters by 16 meters, is made of sandstone masonry. The construction suggests that it was built in the 12th and 13th centuries. Presumably, an Alemannic timber-framed building was added to it in the 15th century. The six floors housed cellars, the great hall, kitchen, living quarters, and servant quarters. The largest room, now called the 'Knight's Hall,' is located on the second floor.
On the north side, the castle complex was protected by a wall with a battlement and two towers. The towers once served as a prison. While the western tower, called the 'Heaven' tower, had barred windows that looked out to the outside, the eastern tower, called the 'Hell' tower, had a 15-meter deep dungeon. The fortifications were connected to the city wall.
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.