Kastelholm Castle: A Medieval Royal Fortress in Finland
Site at a Glance
- Rating
- 4.4
- Popularity
- Medium
- Country
- Finland
- Primary era
- Medieval
- External website
- Open
- Eras represented
- Medieval, Early Modern
- Civilizations
- Swedish
- Site type
- Military
- Remains
- Castle
On this page14 sections
History
Kastelholm Castle is a medieval fortress in Finland, built by the Swedes on Åland near present-day Sund. Construction began in the late fourteenth century, although its exact date is unknown, and the castle was first mentioned in 1388. A wooden fortification stood on the site before the later stone castle. Kastelholm became Åland’s administrative center and later an important royal stronghold, prison, and residence during the political struggles of the fifteenth and sixteenth centuries.
Foundation and medieval administration
The first recorded reference to Kastelholm came in 1388, when parts of the estate of Bo Jonsson Grip, a powerful Swedish nobleman and the castle’s first recorded occupant, were transferred to Margaret I of Denmark. Margaret was a Scandinavian monarch who ruled Denmark and helped establish the Kalmar Union. Following the transfer, Åland became a separate administrative area with Kastelholm at its center. A fourteenth-century tax unit called a rok helped support the castle’s maintenance.
In 1418, Åland became an independent fief, meaning territory granted by a ruler to an administrator in return for service, under the Danish nobleman Bengt Pogwisch. After his death, his widow Ida Königsmarck retained the fief, provoking opposition from Swedish interests. During the Engelbrecht rebellion, a fifteenth-century Swedish uprising against the ruling Danish king and his administration, forces acting for the Swedish nobleman Erik Puke besieged and captured Kastelholm in September 1434. Puke intended to keep the castle as his own fief, but he was executed in 1437.
Political and military importance
Kastelholm reached its greatest political and military importance during the fifteenth and sixteenth centuries. Between 1470 and 1520, its commanders were members of the Swedish Privy Council, although the castle alternated between being granted as a fief and being administered directly for the Crown. In 1485, Niels Eriksen Gyldenstjerne, a Danish royal official, received Kastelholm as a fief and was ordered to repair and improve it for the Swedish Crown. Further rebuilding and expansion followed during the fifteenth century.
Gustav Vasa, who later founded Sweden’s Vasa dynasty and became king in 1523, made substantial additions to the castle before his accession. He frequently hunted in the surrounding forests, which were legally protected and reserved for the king and the castle’s governor. Kastelholm’s position near a maritime route gave it continuing military and administrative value, but its possession remained contested.
Danish forces captured Kastelholm in the early sixteenth century. The more precise surviving date for the seizure is 1507, when the castle was stormed, looted, and burned, and Sten Tureson was taken prisoner to Denmark. After the Danish withdrawal, Kastelholm returned to the Swedish Crown. Hemming Gadh, a Swedish churchman and political figure, held the castle in 1514 or 1515 and remained there for four years. His statement that he had “built” the castle probably referred to repairs following the 1507 attack. He lost the fief in 1518 after criticizing the Swedish regent Sten Sture the Younger.
Denmark regained Kastelholm in September 1520, and Danish control lasted until July 1523. The garrison then surrendered as Swedish forces prepared a major campaign, and Swedish troops occupied the abandoned castle. After Gustav Vasa became king, he granted Åland to Ivar Fleming, a Swedish nobleman who served until 1537 as Kastelholm’s last feudal governor. The castle was subsequently placed under the king’s household administration and managed by royal bailiffs. Repairs continued through the 1540s and probably into the 1550s after the castle had been reported badly damaged.
Royal residence and dynastic imprisonment
Kastelholm retained a role in royal affairs during the sixteenth century. Its shipyard employed about 50 shipwrights, and its records contain the first documented evidence of Roma people in Finland, dating from 1559. Gustav Vasa spent several months at Kastelholm in 1556. His son John, later King John III of Sweden, stayed there in 1557, 1559, and 1561, and became Duke of Finland in 1556.
In 1571, John III imprisoned his deposed brother, King Eric XIV, and Eric’s wife, Karin Månsdotter, at Kastelholm. Eric’s prison room is traditionally identified as a small chamber on the third floor of the central tower, Kurtornet. John III had granted Kastelholm to the queen dowager Catherine Stenbock for life in 1569.
War, fire, and decline
Kastelholm was contested during the War against Sigismund, a late-sixteenth-century Swedish dynastic and civil conflict between supporters of King Sigismund and Duke Charles. In January 1599, Arvid Stålarm took the castle for Sigismund and appointed Salomon Ill as commander. Forces loyal to Duke Charles, later King Charles IX, failed to retake it in April and July. The decisive assault came on 31 July under Admiral Joakim Scheel. Heavy artillery forced the castle to surrender, and its officers were taken to Turku for execution. The fighting caused severe damage.
The castle’s defensive importance declined in the early seventeenth century. A fire in late autumn 1619 caused further destruction, after which Gustavus Adolphus ordered Governor Stellan Otto von Mörner to arrange repairs. The master builder Hans Esslinger directed the work, which continued until 1631. Kastelholm lost its position as Åland’s administrative center in 1634, when Åland was incorporated into Åbo and Björneborg County, a historical Swedish administrative county covering parts of present-day Finland.
The castle then deteriorated rapidly. By 1642, overall responsibility had been reduced to a clerk and a watchman, although Kastelholm continued for a time as a prison. One prisoner was Claes Bielke, a Swedish nobleman convicted in connection with the Linköping Bloodbath. King Charles XI and his mother, the queen dowager Hedvig Eleonora, visited Kastelholm in 1672. It is uncertain whether they stayed in the castle or at the nearby royal estate. The visit later inspired the opera The Hunting of King Charles by the composer Fredrik Pacius and the writer and historian Zachris Topelius.
During the Great Wrath, the period of Russian occupation and warfare in Finland during the early eighteenth century, Kastelholm’s defenses were temporarily strengthened with wooden stakes, but the castle did not face an enemy attack. A major fire in 1745 badly damaged the complex, and the surviving northern wing was used as a granary. Kastelholm was abandoned in the 1770s. By the early nineteenth century, its administrative functions, including the post office and the Russian commandant’s secretariat, had moved to Bomarsund.
Preservation and modern interpretation
Interest in Kastelholm revived during the nineteenth century. Karl Bomansson published a history of the castle in 1856, and the Antiquarian Commission, founded in 1884, included the ruins in its preservation program. Conservation work began in the 1890s. Local farmers used the castle as a granary and partly as a quarry during the 1930s. The northern wing remained a grain store until that decade, when it was converted into Åland’s first cultural-history museum.
Scientific documentation began in the 1960s, followed by a restoration program initiated by the Åland regional administration in 1979. Major restoration and archaeological excavations took place from 1982 to 1989, helping preserve the surviving structures and remains. The restored castle has served as a museum since the late twentieth century and now houses the open-air museum Jan Karlsgården, which presents traditional Åland buildings and rural life. Archaeological discoveries are shown in a dedicated exhibition. Kastelholm is regarded as one of Finland’s five surviving medieval castles of major architectural importance, alongside Hämeenlinna, Olavinlinna, Raseborg, and Turku, and remains an important cultural site in Åland.
Remains
Kastelholm was originally built on a small island of approximately 1.7 hectares beside a maritime route overlooking a fjord. Water and water-filled moats protected the island, while two or three rows of wooden stakes outside the shoreline impeded landings. The complex consists of a main castle and an outer bailey to the north. The outer bailey is approximately twice as wide as the main castle, measuring about 45 by 25 metres, while the main castle measures about 30 by 20 metres. A defensive wall approximately 3 metres thick encircles the main complex, which was built of brick and mortar.
Main castle and fortified towers
Stone keep and residential wing
The earliest stone layout included a rectangular stone keep and a residential wing. A three-storey building known as the palace stood within the main castle. These elements formed the core of the fortified complex, whose defensive wall enclosed the principal buildings and connected them with the outer areas of the site.
Kurtornet and the gateways
A gate tower was added between the main castle and the outer bailey during the fifteenth century. A second gate tower followed between the outer bailey and the outer perimeter in the sixteenth century. The two towers were later combined into the large central fortified tower known as Kurtornet, or the donjon, the principal tower of a castle. Kurtornet contains the gate leading to the outer bailey. A drawbridge probably stood outside the gate, although its existence remains uncertain. Its small third-floor room is traditionally identified as the prison chamber of Eric XIV.
Chapel and northern buildings
Chapel
The castle included a chapel dedicated to Berard of Carbio and four other Moroccan martyrs. The chapel’s precise location is no longer known, but its dedication forms part of the religious history associated with the complex.
Granary and museum wing
A later-built hall was eventually converted into a granary. The northern wing, the best-preserved part of the castle after the 1745 fire, also served as a grain store before becoming a museum in the 1930s. It now forms part of the castle’s cultural-history interpretation, while objects recovered during excavation are presented in a separate archaeological exhibition.
Condition and archaeological preservation
The surviving castle is only partially restored. Its historic interiors have not survived, although the interior decoration has been reconstructed stylistically. Restoration and archaeological work carried out between 1982 and 1989 helped preserve the standing structures and other remains, while the excavated discoveries provide material for the archaeological exhibition housed at the castle.
