The UN estimates that two-thirds of the world's population will live in massive cities by the year 2050. Some of those cities are well-known. Others are not.

Tokyo is a megacity with one of the highest population densities in the world. (File photo)
Tokyo is a megacity with one of the highest population densities in the world. (File photo)

The UN says that the world will have undergone the largest and fastest period of urban expansion in human history by 2050 as two-thirds of the world's population will then live in cities.

In the 1990s, ten cities around the world were considered 'megacities' with a population of more than 10 million. Since then, the number of such cities has risen to 21.

The shift to a largely urban global population means the work of city planners is changing.

TRT World's Tadhg Enright spoke to an urban planner in London, one of the world's best-known megacities.

Source: TRT World