Kärnan is a medieval tower, the only part remaining of a larger Danish fortress which controlled the entrance to the Baltic Sea.
The origins of the fortress is disputed but Danish legend places its origin to the reign of the legendary King Fróði. However, this legend has not been supported by archaeological proof. Dendrochronological dating has shown that the core was built in the 1310s, when Eric VI of Denmark was King of Denmark. It was considered the most important fortress in Denmark, and was integral in securing control over the strait between Scania and Zealand.
It was surrendered to Sweden along with the rest of Skåneland as part of the Treaty of Roskilde in 1658. The fortress was retaken by Danish forces in 1676 during the Scanian War, and its capture celebrated by flying a giant Flag of Denmark above it. This flag was later captured by the Swedish army and is preserved in the Army Museum (Armémuseum) in Stockholm. The fortress returned to Swedish control by the Treaty of Lund in 1679. Charles XI of Sweden ordered most of it demolished fearing that it was too exposed to a sneak attack from Denmark. The only thing that was saved for posterity was the old medieval tower core. The tower continued to serve as a landmark for shipping through Øresund.
The castle was restored starting during 1893-94, under instructions from Oscar Ferdinand Trapp, a Swedish businessman and engineer (1847–1916). Architect for the restoration was Josef Alfred Hellerström (1863–1931), Helsingborg city architect from 1903 to 1928. The objective of the restoration was to restore, to the extent possible, the appearance the structure had based upon the oldest known medieval illustration. The building's crenellation dates from these repairs.
References:Linderhof is the smallest of the three palaces built by King Ludwig II of Bavaria and the only one which he lived to see completed.
Ludwig II, who was crowned king in 1864, began his building activities in 1867-1868 by redesigning his rooms in the Munich Residenz and laying the foundation stone of Neuschwanstein Castle. In 1868 he was already making his first plans for Linderhof. However, neither the palace modelled on Versailles that was to be sited on the floor of the valley nor the large Byzantine palace envisaged by Ludwig II were ever built.
Instead, the new building developed around the forester's house belonging to his father Maximilian II, which was located in the open space in front of the present palace and was used by the king when crown prince on hunting expeditions with his father.