Borg

Borg stood above the Sarpsfossen waterfall on the Glomma, founded by King Olav Haraldsson in the early eleventh century. Also known as Sarpsborg, the medieval town exported timber, iron and hides. Its position by the river linked the forests and farms of the interior to a route towards the sea. The waterfall and the river bend also helped defend the royal stronghold that gave the town its name.

During the Northern Seven Years' War Swedish troops burned the town in 1567. Its urban privileges were transferred to a new settlement at the mouth of the Glomma, later called Fredrikstad, though some inhabitants remained at the old site. In 1702 a great clay landslide carried much of medieval Borg into the river; settlement continued around Gleng and Sandesund nearby.