Norwegian Wood Festival is a three-day revelry held annually in mid-June at Frognerbadet—an open-air public bath. Since 1992 it has seen a number of established artists such as Sting, Bob Dylan, David Bowie, Roger Waters, Lou Reed and Tori Amos, as well as less known local singers.
The main stage is surrounded by the hills, which ensures that everyone has a good view of the performances. It's also great there's an option to buy a Festivalpass that covers all three days, or "Dagspass" if you wish to be there for just one day. Regarding the age, there are no restrictions—everybody is welcome to join the party.