The Copenhagen December Riot took place on 16 December 2006 in the Copenhagen area of Nørrebro. The spark of the riot was the longstanding conflict over the fate of the alternative left-wing social centre Ungdomshuset (The Youth House). The riot broke out when a Black Bloc demonstration in support of Ungdomshuset was blocked by the police. The riot was the worst of its kind in Copenhagen for at least 13 years and marked a low point in the negotiations between the authorities and the users of Ungdomshuset.