The Princes' House (German: Prinzenhaus) in Plön in the North German state of Schleswig-Holstein is a former royal summer residence in the grounds of the park at Plön Castle. It is the only surviving maison de plaisance in Germany. It was given its present name because at the end of the 19th and beginning of the 20th century it was used as a residence and school for the sons of the German emperor, William II.