The first castle on the site of Schloss Oldenburg was built around 1100 and became the seat of the House of Oldenburg. First recorded in 1275, it was expanded around 1400 into a moated castle. By 1600, it housed a court of 350 people. The central keep was removed in 1608 due to structural issues.
In the early 1600s, Count Anthony Günther began transforming the site into a four-winged palace inspired by Italian city palaces. After his death, the Danish royal family (House of Oldenburg) took control, and the castle was used by Danish governors. Major medieval parts were removed in the 18th century, and a government wing was added in 1744.
From 1773, the Holstein-Gottorf branch ruled the Duchy of Oldenburg. Grand Duke Peter I modernized the palace from 1817, adding new wings. A library wing destroyed by fire in 1913 was rebuilt. The 1744 annex was replaced in 1894 by a neo-Renaissance hall designed by Ludwig Klingenberg.
Grand Duke Friedrich August resided there until his 1918 abdication. The palace became the State Museum in 1919–20 and was publicly owned by 1923.
Today, it houses part of the State Museum for Art and Cultural History, featuring decorative arts and regional history. The palace is located next to Schlossplatz.
References:Doune Castle was originally built in the thirteenth century, then probably damaged in the Scottish Wars of Independence, before being rebuilt in its present form in the late 14th century by Robert Stewart, Duke of Albany (c. 1340–1420), the son of King Robert II of Scots, and Regent of Scotland from 1388 until his death. Duke Robert"s stronghold has survived relatively unchanged and complete, and the whole castle was traditionally thought of as the result of a single period of construction at this time. The castle passed to the crown in 1425, when Albany"s son was executed, and was used as a royal hunting lodge and dower house.
In the later 16th century, Doune became the property of the Earls of Moray. The castle saw military action during the Wars of the Three Kingdoms and Glencairn"s rising in the mid-17th century, and during the Jacobite risings of the late 17th century and 18th century.