Mount Fokas is a 862m high hill in in the area of Corinth. A medieval settlement existed on its trapezoid summit and later a castle was built by the Franks in the 13th century (or perhaps by the Byzantines, a little earlier).
The castle controlled the plains of Nemea and the main route to the center of Peloponnese. It had visual contact with other Frankish castles in the area like Acrocorinth or Agios Vasilios but also with some castles in Central Greece, on the opposite side of the gulf of Corinth.
Only a few ruins of the walls and from the settlement remain at the lower part of the rock.
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.