The specialized book "Friedrichstein" offers a comprehensive and detailed examination of Friedrichstein Castle, which was built in the early 18th century as the family seat of the Counts Dönhoff. This second edition not only includes newly discovered sources, such as the escape report of the last resident of the castle, Count Dietrich Dönhoff, but also features a thorough revision of all texts based on the latest research findings. Additionally, it contains three new contributions that enhance the understanding of the castle's history and architecture. A particular highlight is the digital reconstruction of the castle, created as part of a German-Polish-Russian research project. These reconstructions, along with numerous new illustrations, provide a unique insight into the nearly lost architecture and interior design of the castle and contribute to the preservation of cultural heritage.