NorthSide is Aarhus' major summer music festival, drawing large Danish and international crowds for a programme that usually mixes big names with newer acts. It has also made sustainability part of its identity, which gives the event a more local character than a generic touring-festival stop.
It only matters if your dates line up, but when they do, it can reshape a visit to Aarhus. Book accommodation early, expect busy transport, and treat the festival as a city event rather than an isolated concert field.