After moving to New York alone, writer Olivia Laing discovered the truth about loneliness. She says it is a gift. Eric Klinenberg explains why more and more people are choosing to live alone and why cities like New York must invest in housing stock that singletons actually want to live in, the type of housing they have in Scandinavian countries. In Denmark when someone dies alone, and no-one claims the body, the authorities put an ad in the newspaper calling for Possible Relatives. This is also the title of a photo-book by Danish photographer Tina Enghoff. She tells us about the pictures she took of the apartments after the dead were removed. Some of these bodies went undiscovered for months.