in medieval Danish history, trade centre at the southeastern base of the Jutland Peninsula on the Schlei estuary. It served as an early focus of national unification and as a crossroads for Western–Eastern European and European–Western Asian trade.

One of the earliest Scandinavian urban centres, Hedeby was established in the late 8th century. Its trade, which included slaves, furs, textiles, iron, and weapons, was complimented by a well-developed artisan and industrial establishment. In the early 9th century King Godfred of Denmark built the Danewirk, an earthwork barrier, along the base of the peninsula south of Hedeby to protect the thriving centre from Frankish incursions. Despite this and other precautions, the Danes lost Hedeby for most of the 10th century—first to the Swedes and then to the Franks. Even after King Harald Bluetooth regained Hedeby in 983, the town suffered Norwegian and Wendish Slav raids into the 11th century; by the middle of that century it was abandoned, its activity being transferred to neighbouring Schleswig (ancient Sliesthorp, or Sliaswic).