Location: MarstrandmMap
Constructed: 1658
Carlsten Castle is a citadel on Marstrand island on the coast of the Baltic Sea. It was constructed following the Treaty of Roskilde of 1658 when Swedish Empire acquired large territories. Among these lands was region of Bohuslan that needed protection. Swedish king Carl X of Sweden carried out a massive building campaign of castles, fortresses and smaller forts.
Carlsten Castle was erected under design and supervision of military engineer Johan Vernsheldu. Initially the stronghold was a wooden temporary one, but in 1666 it was replaced by a stone structure. Carlsten Castle was put to use rather quickly. During the Danish- Swedish War of 1675- 79 its walls were stormed by 2000 Danish- Norgwegian troops under command of Danish general Ulrik Frederick Gyldenlove and captured on July 23, 1677 after three weeks of siege. Carlsten Castle was returned to the Swedish crown after diplomatic negotiations. During the Great Northern War fortress was again assaulted and subsequently captured by Norwegian vice- admiral Tordenskjold in 1719. The citadel was again returned in 1720 after diplomatic negations at the conclusion of the Great Northern War.
Carlsten Castle eventually started to loose its importance as a military citadel. Its main tower was transformed into a lighthouse in 1779. Parts of the abandoned stronghold was turned into a prison. Many of the famous inmates were kept here including famous robber Lasse Maya who sat here from 1813 to 1830s. In 1855 last dangerous criminal was transferred from castle to other prisons as the military fortifications were deemed not safe enough. Military garrison finally left the walls of the fortress on May 1, 1882. Between 1907 and 1937 Carlsten Castle housed a school.