The heir of the House of Hanover offered Marienburg Castle to the state for one euro, and his father sued him for gross ingratitude

King George V of Hanover built Marienburg from 1858 to 1867 as a birthday present for Queen Marie. In 1866 Prussia annexed Hanover and the royal family left for Austria. The castle then stood mostly empty for almost 80 years. In 2004 and 2007 Prince Ernst August of Hanover, born 1954, gave Marienburg, the Calenberg estate and the Fürstenhaus Herrenhausen to his son, Ernst August Jr., as an advance on his inheritance. In October 2005 Sotheby's sold more than 20,000 objects from the castle for about €44 million. In 2018 the son announced he would sell the castle, damaged by dry rot and needing an estimated €27 million of work, to the state for one euro. The father objected. The castle and its contents went into a non-profit foundation, which became owner on 2 October 2020. In late 2020 the father sued the son in the Hanover regional court to take back the gifts. Court papers alleged the son had acted "behind his father's back". The son called the suit baseless. In March 2022 the father withdrew and assigned his claims to EAH Betreibungs GmbH of Salzburg. On 1 July 2022 the court dismissed that company's claim: putting the castle in a foundation was not gross ingratitude, and the assignment was invalid. The company did not appeal. In 2026 the castle is closed for repairs planned to run to 2030, with €27.2 million from the federal and state governments.