Allentsteig Castle, located on a rock to the north of Allentsteig and bordered by a former moat to the east, was founded by the Kuenringers around 1000. It remained in the possession of the Lords of Kamegg-Kaya until about 1390.
Around 1500, the Hager family received the estate and transformed the medieval castle into a Renaissance palace between 1544 and 1570. Sigmund Hager, a prominent Protestant, visited Luther in Wittenberg. Paris von Sonderndorf acquired Allentsteig in 1599 and, due to his opposition to the Emperor, the town was plundered and occupied during the Thirty Years' War. In 1629, Hans Friedrich von Sonderndorf lost his estate, which was then acquired by the Rappach family. By marriage, it passed to Count Ernst August von Falkenhayn.
Fires in 1682 and 1752 caused significant damage. In 1804, Baron Leopold von Hahn bought the estate, and it later passed to the Pereira-Arnstein family and the Princes of Liechtenstein. Baroness Maria von Preuschen inherited it in 1918. When the German Reich established the Allentsteig military training area in 1938, the castle became the command center, a role it retained under Austrian control after the Russian occupation from 1945 to 1955.
The outer walls of the five-sided Renaissance structure largely originate from the medieval castle. The oldest parts include the massive keep from the second half of the 12th century with a Romanesque portal and the adjacent eastern quoin wall. The turreted top floor with a tent roof was added in 1904. The castle is accessed from the east through a two-story gate hall from the 16th century, featuring a wide bay window over a Renaissance portal. The inner gate wall, dating to around 1300, is pierced by a Gothic pointed arch from the early 14th century. The windows with profiled stone frames on the outer front date to the late 16th/early 17th century. The three-story rectangular arcade courtyard, marked with 1576, features flat arches on Tuscan columns on three sides. The interior was mostly remodeled in the late 19th century, including historicist tile stoves.
Currently (as of 2016), the castle houses the command of the Allentsteig military training area and the 4th Reconnaissance and Artillery Battalion.
Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.