8 billion-dollar mega projects that will transform the world's greatest cities by 2030

The world is rapidly urbanizing. The United Nations predicts that the number of people living in cities could double by 2050 - to 6.5 billion.

To accommodate growing populations, cities like Paris, New York, and Tokyo are building more housing and public resources, including parks, schools, and subways, as part of large redevelopment plans.

These cities will likely look very different in the coming decades. Take a look at some of the biggest urban projects under construction below.