Bårby Borg was an ancient hill fortification. It was built in two periods, first in the age of migrations and later in the Middle Ages. Bårby Borg is the only hill fort in Öland where a natural steep scarp was used as part of the fortification. The other sides were protected by stone wall. The diameter was approximately 150 meters. Archaeologists have found a gold coin from the ruins made in Byzantine Empire in the 6th century AD.
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Dunluce Castle is a ruined medieval castle located on the edge of a basalt outcropping in County Antrim, and is accessible via a bridge connecting it to the mainland. The castle is surrounded by extremely steep drops on either side, which may have been an important factor to the early Christians and Vikings who were drawn to this place where an early Irish fort once stood.
In the 13th century, Richard Óg de Burgh, 2nd Earl of Ulster, built the first castle at Dunluce. The earliest features of the castle are two large drum towers about 9 metres in diameter on the eastern side, both relics of a stronghold built here by the McQuillans after they became lords of the Route.
The McQuillans were the Lords of Route from the late 13th century until they were displaced by the MacDonnell after losing two major battles against them during the mid- and late-16th century.
Later Dunluce Castle became the home of the chief of the Clan MacDonnell of Antrim and the Clan MacDonald of Dunnyveg from Scotland.
In 1588 the Girona, a galleass from the Spanish Armada, was wrecked in a storm on the rocks nearby. The cannons from the ship were installed in the gatehouses and the rest of the cargo sold, the funds being used to restore the castle.
Dunluce Castle served as the seat of the Earl of Antrim until the impoverishment of the MacDonnells in 1690, following the Battle of the Boyne. Since that time, the castle has deteriorated and parts were scavenged to serve as materials for nearby buildings.