{{Short description|Small castle in Sønderborg Municipality, Denmark}} [[File:Nordborg Slot.JPG|thumb|340px|Nordborg Slot]] '''Nordborg Castle''' ({{langx|da|Nordborg Slot}}) is a small [[castle]] which lies on the southern side of Nordborg Lake (''Nordborg Sø'') in [[Nordborg]] on the island of [[Als Island|Als]] in [[Sønderborg Municipality]], [[Denmark]]. The castle premises are currently used by Nordborg Slots Efterskole as a [[boarding school]]. Nordborg Castle has also been the backdrop for a number of years for Nord-Als Musikfestival. <ref>{{cite web|url= https://www.kroneborg.dk/280/nordborg-slot|title = Nordborg Slot|website= kroneborg.dk|access-date=August 1, 2020}}</ref>

==Founding and early history== According to [[Saxo Grammaticus|Saxo]], Nordborg Castle was founded by King [[Sweyn III of Denmark|Svend Grathe]] (c. 1125–1157) under the name '''Alsborg'''. Hence, it can be dated to around 1150. Alsborg was built while the [[Wends]] still dominated the Danish coast; its location a few kilometers inland meant that the castle could not be attacked without warning, and the local population had a better chance of taking refuge there. <ref>{{cite web|url= https://denstoredanske.lex.dk/Svend_3._Grathe |title = Svend 3. Grathe|website= Den Store Danske|access-date=August 1, 2020}}</ref>

The first written evidence of Alsborg is from the end of the 12th century. From this, it is known that [[Valdemar of Denmark (bishop)|Bishop Valdemar of Slesvig]] (1158-1236) was held prisoner at Alsborg between 1192 and 1197. <ref>{{cite web|url= https://runeberg.org/dbl/18/0195.html|title = Valdemar (Knudsen), Biskop af Slesvig |website= Dansk biografisk Lexikon |access-date=August 1, 2020}}</ref>

After [[Sønderborg Castle]] was built at the south end of the island of Als (ca. 1158), Alsborg was renamed '''Nordborg''', literally "northern fortress" (compare English "[[Norbury]]"). Nordborg was for a large part of the [[Middle Ages]] the property of the king, and was on several occasions a source of income for the king's widow.

In 1571, [[Frederick II of Denmark|King Frederick II]]’s brother [[John II, Duke of Schleswig-Holstein-Sonderburg|Hans the Younger]] (1545–1622) inherited his mother [[Dorothea of Saxe-Lauenburg|Queen Dorothea]]'s possessions of [[Als (island)|Als]] and [[Sundeved]] including Nordborg. Hans was an enterprising man, who in the next 50 years constantly expanded and improved his properties. There was a series of building projects in and around Nordborg Slot.<ref>{{cite web |url= https://runeberg.org/dbl/6/0574.html |title =Hans (den yngre), Hertug af Sønderborg |website= Dansk biografisk Lexikon|access-date=August 1, 2020}} </ref>

Upon Hans' death in 1622, his possessions were divided into separate dukedoms, including Nordborg, which went to his son [[John Adolph, Duke of Schleswig-Holstein-Sonderburg-Norburg|Hans Adolf]] (1576-1624). Hans Adolf died only two years later and so the dukedom then went to Hans the Younger's other son [[Frederick, Duke of Schleswig-Holstein-Sønderburg-Norburg|Frederik]] (1581-1658). <ref>{{cite web|url= https://runeberg.org/dbl/6/0576.html |title = Hans Adolf, Hertug af Nørborg |website= Dansk biografisk Lexikon|access-date=August 1, 2020}}</ref> <ref>{{cite web|url= https://runeberg.org/dbl/5/0342.html|title =Frederik, Hertug af Nørborg (Nordborg) |website=Dansk biografisk Lexikon|access-date=August 1, 2020}}</ref>

==Occupation and fire== Nordborg was occupied several times during the [[Second Northern War|Swedish wars]], first by the [[Swedish Empire|Swedes]], then by the [[Brandenburg-Prussia|Brandenburgian]] and [[Polish–Lithuanian Commonwealth|Polish]] troops and finally by Swedish troops until [[Treaty of Copenhagen (1660)|peace came in 1660]].

In 1665 fire broke out in the castle, and it burnt down. Duke Hans Bugislav (1629-1679) went bankrupt and forfeited his estate, which reverted next to August, Duke of Schleswig-Holstein-Sonderburg-Plön (1635-1699). In 1678 rebuilding of the castle began, and at this time the ducal [[coat-of-arms]] was placed over the castle entrance. In 1730, Nordborg was taken back into crown possession. Nordborg had an estate of around 400 hectares, but in the following decades the land was turned into farms and in 1766 the castle was sold to a private owner and some of the buildings were demolished and sold for building materials. <ref>{{cite web|url= https://runeberg.org/dbl/1/0395.html|title = August, Hertug af Nørborg |website= Dansk biografisk Lexikon |access-date=August 1, 2020}} </ref>

==High school and boarding school== In 1909 the castle was purchased by Nordborg town. It was the pro-German Mayor Klinkers' dream to build a high school, which would be a counterweight for the Danish high schools north of the border. The castle was thereafter restored by the architect Eugen Fink, and in 1910 the castle was leased out to the German high school association in [[South Jutland County|Northern Schleswig]].

After the reunification in 1920 the castle was bought by the merchant Johan Hansen (1845-1928). He established at foundation (''Stiftelsen Nordborg Slot'') which since 1922 has run the boarding school, Nordborg Slots Efterskole, at the castle.

== Owners of Nordborg Castle == *(ca. 1150-1490) Between the Crown and the Sønderjyske dukes *(1490-1564) the Crown *(1564-1622) Duke Hans den Yngre *(1622-1624) Duke Hans Adolf *(1624-1658) Duke Frederik *(1658-1669) Duke Hans Bugislav *(1669-ca. 1672) the Crown *(ca. 1672-1676) Johan Adolf of Pløn *(1676-1699) Duke August of Nordborg-Pløn *(1699-1722) Duke Joachim Frederik *(1722-1729) Arvingerne til Duke Joachim Frederik *(1729-1766) the Crown *(1766-?) Hans Bugislav Carstens *(?-1830) various owners *(1830-?) Momme Steffens *(?-1909) unknown owner *(1909-1921) Nordborg town *(1921) Johan Hansen *(1921-) Nordborg Slot Foundation

==References== {{Reflist}}

== External links == * [http://www.kulturarv.dk/1001fortaellinger/da_DK/nordborg-slot Nordborg Castle] {{Webarchive|url=https://web.archive.org/web/20100508195157/http://www.kulturarv.dk/1001fortaellinger/da_DK/nordborg-slot |date=2010-05-08 }} on the ''1001 stories about Denmark'' website (Danish language) *[https://www.musikfestival.dk/ Nord-Als Musikfestival website] *[http://nse.dk/ Nordborg Slots Efterskole website]

{{Denmark castles and manor houses}} {{Castles in Denmark}} {{Coord|55|03|32.6|N|9|44|54.6|E|display=title|type:landmark_region:DK}}

[[Category:Castles in Denmark]] [[Category:Buildings and structures in Sønderborg Municipality]] [[Category:Als (island)]]