As the 21st Century unfolds, our sprawling cities are set to grow and grow even more. A recent UN report suggested that by 2050, three-quarters of humanity will live in our swelling cities.
The massive influx to our planet’s urban populations could create a whole host of problems – from overcrowding to air pollution, extra stress on natural resources and loss of habitats to grow more food.
How can our future cities cope with the added burden of increasing populations? Here, three experts taking part in BBC Future’s Building Tomorrow series talk about the challenges of tomorrow’s cities – and what we need to do to make them better places to live in.