Early history Excavations in 1980s indicated that a
Karelian fortress pre-dated the castle built by the Swedes in 1293. The oldest layers of occupation have been discovered in the so-called Smith's Courtyard. A man-made breastwork of sand with timber posts was found from this area. Also charred remains of buildings, which some were linked to the breastwork, were also found. Tjulenev suggests that the Karelian fort had a wooden tower. Tjulanev's several finds from the area include a bent sword which was dated to the period between 1130 and 1200.
Medieval history Construction of the next phase of the fortress started in 1293 by orders of
Torkel Knutsson,
Lord High Constable of Sweden, who in the 1290s made a supposed
crusade against
Karelia, the
Third Swedish Crusade. The crusade was part of the ongoing
Swedish–Novgorodian Wars, against the Russians of the
Novgorod Republic. Knutsson chose the location of the new fortress to control the
Bay of Vyborg, which was bordered by trading sites long used by the local population. From the bay, a navigable river passage goes inland, ultimately connecting the place with several districts, lakes, and, indirectly by
portage, with rivers flowing into
Lake Ladoga. In 1364,
Albert III of Mecklenburg was proclaimed
king of Sweden, and in accordance with the German model he began to divide the castle fiefs, which were immense in Finland, into smaller provinces. In some instances, these new, smaller provinces were given separate
bailiffs' residences which have since disappeared; this was the case with the
Linnavuori castle mound in
Porvoo () and the castle of
Korsholm in
Ostrobothnia, near the modern-day city of
Vaasa which was founded later. Only earthworks remain at these sites, but in two places, still-extant though now ruined stone strongholds were built:
Raseborg Castle, in western
Uusimaa (west of
Helsinki), and
Kastelholm Castle, in
Åland. The castle and the large surrounding fief became a virtually
autonomous principality. Its governors were usually enfeoffed with the incomes of the county. The
fief of Viborg became known as a
margraviate. Its governors were generally from the most powerful families of the kingdom. They enjoyed large administrative powers at a significant distance from the capital. These realities made them practically independent rulers. The castle of
Savonlinna,
Olavinlinna (built in the 1470s), was usually subjugated to Viborg. Prominent men who held Viborg as their fief included
Bo Jonsson (Grip),
Christer Nilsson Vasa (1417–42),
Karl Knutsson Bonde (1442–48, the future king),
Eric Axelsson Tott (1457–81),
Knut Posse (1495–97),
Sten Sture the Elder (1497–99, between his regencies),
Eric Bielke, and Count
John of Hoya. Particularly in the 1440s and the late 15th century, the fortresses were further enlarged. The first mention of firearms in Finland relates to Viborg castle in 1429. During the Middle Ages the Russians repeatedly besieged the castle, most famously in 1495 during the
Russo-Swedish War (1495–97) while
Knut Posse was governor of the castle. The situation of the defenders looked hopeless, but they were saved by the
Viborg blast on 30 November 1495 (
St. Andrew's Day), a mysterious explosion which scared the Russians away after they believed they had seen a Saint Andrew's cross in the sky.{{cite web|url= https://sok.riksarkivet.se/sbl/Presentation.aspx?id=7380 |title=Knut Posse |website=Svenskt biografiskt lexikon File:VyborgCastle1710.jpg|Simulation of Viborg castle ablaze in 1710, after the Russian attack in the Great Northern War Image:Viborgs slott 1840.jpg|
Vyborg Castle Torsten Wilhelm Forstén: 1840 File:Severin Falkman - Karl Knutson Bonde Leaving Vyborg Castle for the Royal Election in Stockholm 1448.jpg|
Charles VIII leaving Vyborg Castle to the election of the new king in 1448, , 1886
Modern history In the 16th century, much was renovated and additions were made. In the 17th century, the castle was allowed to decay, as Russian danger was lessened and the border was further eastwards.
Viborg was taken by the Russians in 1710, but passed back to Finnish hands in 1812 when all of
Old Finland was attached to the autonomous
Grand Duchy of Finland. The castle owes its present appearance to extensive restorations undertaken in the 1890s. The military of the
Russian Empire used the castle until 1918 for housing administration. belonged to the newly independent Republic of Finland between 1917–40 and again 1941–44. As a result of
border changes in
World War II it was annexed by the
Soviet Union in 1944. ==Architecture==