In 1800, London was the only city in the world with a population of a million people.
The number of cities with 5 million inhabitants or more will pass from 41 in 2000 to 59 in 2015. Among those cities, the number of 'mega-cities' (those with 10 million inhabitants or more) will increase from 19 in 2000 to 23 in 2015.And a graph showing rural and urban population shifts that you will probably see better by going there yourself:
