The Historical Museum is actually three museums under one roof. Most interesting is the ground-floor National Antiquities Collection (Oldsaksamlingen), which has displays of Viking-era coins, jewellery and ornaments, and includes the only complete Viking helmet ever found. Look out for the 9th-century Hoen treasure (2.5kg), the largest such find in Scandinavia. A section on medieval religious art includes the doors and richly painted ceiling of the Ål stave church (built around 1300).
The 2nd level has an Arctic exhibit and the Myntkabinettet, a collection of the earliest Norwegian coins from as far back as AD 995. Also on the 2nd level, and continuing on the top floor, is the Ethnographic Museum, with changing exhibits on Asia, Africa and the Americas.