Christiania is an old military base in Copenhagen that was occupied by leftist youths in the seventies. At the time, it was somewhat common to squat old abandoned buildings, but few remain today. Christiania is one of the few squats that ended up with a semi-legal status. Today it's mostly known as a place where you can easily buy weed, even though that's very much illegal in Denmark. Whether it's still controlled by leftists, or by drug selling gangs, is somewhat up for debate. In any case, this is their unofficial anthem, written in 1975. I think the idea that you can't fight revolutionaries with all your power because they're your own children is a very powerful one: