At Ytraberget are the ruins of a stone fortress from the age of migration, dated 300 years before Viking times (550-1050 AD.)
The fortress was probably used during the Battle of Hafrsfjord in the year 872. The outermost crag is steep and difficult to negotiate. If you take a closer look, you'll see remnants of stone walls around the whole plateau, as well as ruins where houses stood.
In 1972 King Olav V signed a monumental stone out at Ytraberget in connection with the 1100th anniversary of the Unification of Norway (872 AD).