Gamleborg

Gamleborg, also referred to as Gamleborg Viking Fortress, became the primary citadel on the Danish island of Bornholm. Built round 750 AD, it was the seat of the kings of Bornholm throughout the Viking age and early Middle Ages. The large citadel is 264 metres lengthy from north to south and a hundred and ten metres huge from east to west, with gates to the north and southwest. Around 1100, considerable changes were made and it turned into strengthened, but it became deserted quickly afterwards in favour of Lilleborg Castle, roughly seven-hundred metres to the northeast. The fort is Bornholm's oldest defence works.

Its builder is unknown, but an account of the Baltic Sea travels of Wulfstan of Hedeby in 890 tells us that Bornholm already had its own king on the time. There is, however, company proof that the citadel became in use at some point of the reigns of Harald Bluetooth and Canute IV. The Gamleborg fort became used as safe haven during the tenth century in opposition to Viking raids. Gamleborg was deserted in 1150, the occupants shifting to Lilleborg, most effective 700 metres to the northwest.