By 2050, humanity will amount to 9,000 million people. More than 70 % of the world’s population will live in metropolises. Cities must get prepared for the changes that have already begun. They will face the biggest challenge of the 21st century. The reading of the book “Triumph of the City”, written by Edward Glaeser, was the trigger and inspiration for this documentary. Gleaser points out a large part of the conflicts that cities face now and in the future.