Complex sentence: Notodden is famous for the annual Notodden Blues Festival, which is considered one of the best blues festivals in Europe, but they also have a famous metal festival called Motstøy Festivalen.
Split into simpler sentences: Notodden is famous for the annual Notodden Blues Festival, which is considered one of the best blues festivals in Europe. But they also have a famous metal festival called Motstøy Festivalen.