In La Ferté-Milon stand the ruins of an unfinished castle, whose façade was 200 m long and 38 m high. The first castle was erected already in the 9th century AD, but the current structure dates from 1393, when Louis of Orléans started to reconstruct a strong castle. It was cancelled in 1407, when Louis was assassinated.
The singular form of the tower walls was probably designed to resist cannons and protect the gate. The façade is preceded by a moat. On the right is a square tower of which two bare walls remain. The top of the ramparts is adorned with machicolation. Access to the town was protected by a former gate of which two towers remain. Behind the ramparts, two 160 mm cannons from 1909 sit facing towards the valley.
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.