The Burg Rheinstein is a castle near the town of Trechtingshausen in Rhineland-Palatinate, Germany. The castle was constructed in about 1316/1317. Rheinstein Castle was important for its strategic location. By 1344, the castle was in decline. By the time of the Palatine war of succession, the castle was very dilapidated. During the romantic period in the 19th century, Prince Frederick of Prussia (1794–1863) bought the castle and it was rebuilt.