The seventh session of the World Urban Forum, started Saturday, is set to discuss a wide range of urban issues facing the world today inColombia’s second largest city and 2013′s most innovative city of the year, Medellin.

Cities are the future of the world. Over half the world's population lives in cities, and by the middle of the century more than seven in 10 people will live in cities, according to the United Nations. Almost all this urban growth will take place in emerging economies.