According to The New York Times:
Rheinfels Castle, which…was once a property of the Hohenzollern family, has been owned by the town of St. Goar since 1924. A condition set at the time was that the town not sell the castle, failing which the Prussian crown estate administration reserved the right to revoke St. Goar’s ownership.
Prince Georg Friedrich of Prussia, …the current head of the Hohenzollern family, argued that a 1998 agreement under which St. Goar granted the hotel next to the ruins a 99-year leasehold amounted to a sale. But the Koblenz state court rejected his case for the site’s return.
To read the entire article in The New York Times, please click here.