Copenhagen, Denmark. Starting in the beginning of june, on the wednesday before the first weekend but may vary.
Four days of partying, each day in a different neighborhood adding to the flavor and diversity. Lot s and lots of small blocks and larger scenes with electronic music of all sorts. Every day has an after party with the saturday party being more club-like.
Its free (on the street where the best parties are) , its always sunny this time of year and people are super friendly. Around 100.000 participants during the four days.