You can hop on and off as many times as you like aboard this City Sightseeing open-top, double-decker bus. There are 17 stops, and the entire route takes approximately 90 minutes. The bus departs every 30 minutes from each stop. Tickets are valid for 24 hours only.Oslo, the oldest and sunniest of the Scandinavian capitals, was founded by Harald Hadrade in the 11th century and is surrounded by mountains at the head of a 70-mile (100 kilometer) fjord. You can visit Akershus Fortress, or feel like a real Viking at the Viking Ship Museum.