After the Wittenberg capitulation, Ronneburg Castle came into the possession of the Ernestine Duchy of Saxony in 1548. Since then, Ronneburg Castle has served as the administrative seat of the Wettin Office of Ronneburg, which from the 16th century was under the sovereignty of the following Ernestine duchies due to several divisions over the course of its existence: Duchy of Saxony (1554 to 1572), Duchy of Saxony-Weimar (1572 to 1603) , Duchy of Saxe-Altenburg (1603 to 1672), Duchy of Saxe-Gotha-Altenburg (1672 to 1680), Duchy of Saxe-Eisenberg (1680 to 1707), in turn Duchy of Saxe-Gotha-Altenburg (1707 to 1826). When the Ernestine duchies were reorganized in 1826, the castle, office and city of Ronneburg again became part of the Duchy of Saxony-Altenburg. After the administrative reform in the duchy, they belonged to the Eastern District (until 1900) or to the Ronneburg district office (from 1900). After the Second World War, the new castle temporarily housed a pioneer's house, classrooms from the castle school, an after-school care center and the creative circle. In later times, the city library, the city and school museum, the club rooms of the local history association and the youth club were located in the building.[5] The castle courtyard and the castle garden were redesigned as part of the 2007 Federal Garden Show.