The castle of the Rojas is located on the top of a hill near the town of Poza de la Sal. At the end of the 9th century Count Diego Rodríguez Porcelos repopulated Poza building the castle for the defense of the new territory. Like other castles of this time it may have been a simple keep surrounded by some walls.
In the 14th century Rodriguez de Rojas family rebuilt the current castle. It was occupied in 1808 by French troops and was a target of continuous attacks of Burgos garrisons until the end of the war.
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.