The history of the Sandbjerg Estate goes back to the beginning of the 16th century. In 1564 the estate became the property of Duke Hans the Younger (1545-1622), when his brother Frederik II transferred ownership of a third of the royal duchies to him - an area which included Ærø, Als, and Sundeved in the Duchy of Schleswig.
The Duke left his mark on the landscape, commissioning the building of a dam -which exists to this very day - in a cove of Alssund. The subsequent dammed area became known as Møllesøen (the Mill Pond). The water mill, the ruins of which can still be seen, was operational until it was destroyed by fire in 1916.
On Duke Hans' death in 1622 Sandbjerg became the property of the Sønderborg line of his family. After a bankruptcy in 1667, the estate once more became the property of the Crown. A few years later, in 1673, ownership of the estate changed hands yet again - this time being sold to Prefect (later Chancellor) Conrad Reventlow of Haderslev (1644-1708). The king gave him permission to create an entailed estate incorporating Sandbjerg and his other possessions in Sundeved under the name of the Reventlow-Sandbjerg Estate.
The Sandbjerg owned by Hans the Younger was situated on the site of the present Sandbjerg Farm, on the other side of the Mill Pond. In 1788 Conrad Georg Reventlow built a manor house on the point facing out across the sound. The master builder on the project was Christian August Bohlsmann of Sønderborg. The tenant farmer's house, built in 1783, the manor house, the various other buildings, and the park, all of which are to be found between the Mill Pond and the sound, comprise the present Sandbjerg Estate.
Sandbjerg remained in the hands of the Reventlow family until 1930. For a period during the 1850s The manor house was used as a residence by General Frederik Bülow, victor of the BattIe of Fredericia in 1849. He died at Sandbjerg and is buried in the churchyard at Dybbøl.
After the war of 1864 the duchies of Schleswig and HoIstein were annexed by Germany. North Schleswig was not returned to Denmark until 1920.
In 1924 Sandbjerg was converted from an entailed estate into fee simple, and folIowing the death of the last Reventlow in 1929, the estate was sold to Knud Dahl, a barrister from Copenhagen, and his wife, Ellen Dahl (née Dinesen), both of whom were well known in Southern Jutland for their involvement in matters relating to the borderlands of Denmark and Germany. Like her famous sister, Karen Blixen, Ellen Dahl was artistically gifted. After the death of her husband, she opened the doors of Sandbjerg to scholars and academics, and in 1954 bestowed the entire estate on the University of Aarhus. On her death in 1959, the University acquired full disposal over the Sandbjerg Estate.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.