What do you imagine cities will be like in the future? Will we have smart buildings and flying cars? Or robots that will pick up our rubbish? What about schools? Will we still travel to school or will we study online from home? Perhaps all the buildings and roads will be underground and we'll just have parks and cycle lanes（自行车道）above. Maybe…or maybe not, but what we do know is that in the future, cities are going to have more and more people living in them.
More than half the world's people already live in cities, and by 2050, cities will become homed to about 6.5 billion（十亿）people. That's a lot of people and very little space! More people means that we're going to have more pollution, traffic and noise. It also means that we'll need more homes, schools, hospitals, jobs and transport. We'll need more water, oil, coal（煤）and electricity. Oh, more ways to grow food for so many people!
Many cities are already planning for the future. For example, Bristol is a cycling city in England. You can ride a bike in cycle lanes which are separated from the traffic. To save land, people in Singapore and Tokyo grow vegetables in tall buildings, called "vertical farms". And in Amsterdam in the Netherlands, there are "floating houses" built on water instead of on land!
