To be privately owned
Blomenburg Castle

Blomenburg Castle in Selent, Plön district, is a historicist hunting lodge from the mid-19th century. It is named after its builder, Count Otto von Blome.
History+
Count Otto von Blome acquired the lands of the Lammershagen estate in 1829, which included the building site of the later Blomenburg on the Heidberg near Selent. Between 1844 and 1848, he had a new hunting lodge built there, conceived as a counterpart to the Hessenstein, an observation tower built by Landgrave Friedrich von Hessen. After the Count's death, his daughter Adeline Countess von Hardenberg resided in the castle from 1878 to 1908. Until 1927, Blomenburg served as an occasional residence for the Blome family before being sold to the Provincial Association of Schleswig-Holstein. In the following decades, the castle was used as a youth and educational home, during which much of the original interior furnishings were lost. After the home closed in 1992 and a brief period as refugee accommodation, Blomenburg was converted into a technology center in 1997 and renovated and expanded from 2004 to 2006. Following financial difficulties and insolvencies in 2009 and 2011, its use as a technology center ceased.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://schloesserrundschau.de/schleswig/schloesser/ploen25.html
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 54.2855, 10.4314