North Sea Round Town festival - 22 Juni-8 July (Rotterdam)
Every year Rotterdam city is hosting the big Intrentaional Jazz Festival , the North See Jazz Festival. This year it takes place in the weekend between the Protected content in Ahoy. As a warmup for the festival, the North Sea Round Town takes place - meaning more than Protected content , exhibitions, master classes, lectures, jam sessions, street performances and afterparties, spread over two weeks in various locations arround Rotterdam (and almost all of them are for free!).
For more info about the program of both happenings, you can check the following links:
I warmly recomend it!