Książ Castle (Polish: Zamek Książ, pronounced [kɕɔ̃ʂ]; Silesian: Szlos Fyrsztasztajn, Lower Silesian: Schlooß Ferschtensteen German: Schloss Fürstenstein) is a castle in northern Wałbrzych in Lower Silesian Voivodeship, Poland. The largest castle in the region of Silesia, it is the third-largest in Poland behind Malbork Castle and Wawel Castle. It lies within Książ Landscape Park, a protected area located in the Sudeten Mountains and Sudeten Foreland. The castle overlooks the gorge of the Pełcznica river and is one of Wałbrzych's main tourist attractions.