A very nice interactive world city populations map, past - future. I was surprised by the data from Amsterdam.
The Global Urban Transformation
This map visualises the radical transformation that has occurred across the globe in the last 60 years, from a 30% urban world in 1950, to a 54% urban world in 2015 and a predicted two-thirds urban world in 2050. In 1950 there were 740m people living in cities; there are now 4 billion, rising to a predicted 6.3b by 2050. The circles on the map are proportional to city populations in 1950, 1990, 2015 and 2030. Move your mouse over cities to explore their detailed dynamics. Data is from the UN World Urban Prospects.