A drab collection of four-storey buildings in a rough area of Copenhagen has become a potent symbol of Denmark's struggles with integrating Muslims in the wake of last week's attacks. The Mjoelnerparken neighbourhood was the home of 22-year-old Omar El-Hussein, the Danish-born man of Palestinian origin who is believed to have carried out the attacks that killed two people. "It's important to take these young people seriously," said Mehdi Mozzafari, an Iranian-born specialist on Muslim extremism at Aarhus University in western Denmark. The heavily immigrant towns around France's major cities have become a byword for failed integration, with residents, many of them Muslim, feeling an overwhelming sense of abandonment.