Martinsburg Castle with its powerful hexagonal tower was built around 1324 as a toll station on the Rhine bank in Oberlahnstein. It was a toll castle in the Electorate of Mainz. The pictorial assembly was built together with the town fortification.
The pointed gate in the east wall shows a delicate cast iron oriel with emblem (1395). The north wing probably contained the main rooms. The apartment tower in the northwest, built in the 14th century, was modified in the 18th century. The south wing is likewise Gothic. The archbishop Franz Lothar von Schönborn established the southwest and west wing between 1719 and 1721; there the main tower (end of the 14th century) is assembled; at its windows one sees outside small console stones for the fold-down wooden shutters. The roof dates from the 18th century.
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.