In this, the first of six volumes, the main results of the excavations which the University of Oslo carried out at Kaupang 1998-2003 are presented. A completely new picture is put forward of the port that the adventurer Ohthere visited in c. 890. It is now clear that Kaupang was one of the four Scandinavian towns that were founded around the year 800. Kaupang is connected to the power centre of Skiringssal, to the Ynglings - the legendary Norwegian royal lineage, and to the King of the Danes - the dominant political actor in south-west Scandinavia.