The market and central mosque in Nigeria's capital Lagos, which almost doubled in population to 14m over the last 15 years . Photo / Frederic Soltan, Getty
With more and more people choosing to live in cities rather than in the countryside, many of the world's urban areas are growing at an astonishing rate.
This incredible map shows the speed at which people are moving to cities in China, India and Africa, with much slower urban growth happening in parts of Europe and the US.
African cities - especially those in Nigeria - are seeing the most dramatic growth while the US cities of Pittsburgh, Cleveland and Detroit are starting to see people leave.
With the global population expected to reach 9.5 billion in 2075, many of the world's giant cities - particularly in the developing world - are quickly filling up.
The map lists 500 cities with over 1 million people, and is shaded based on yearly population growth rate between 2000 and 2016.
Percent growth corresponds with darker shades of teal, while orange shows negative growth over the time-frame.
According to Berlin-based chart-making website Datawrapper, Chinese cities are among the fastest growing.
The chart, which uses UN data from between 2000 and 2016, shows some smaller Chinese cities such as Suqian in the north east and Putian in the east growing at around 6 per cent every year.
This is six times faster than London's growth over the same period and 20 times faster than New York's, which is growing at just 0.3 per cent per year.
Parts of Africa have also been expanding at a rapid rate, with Abuja in Nigeria seeing a 7 per cent annual increase between 2000 and 2016.
These are among the fastest growing cities in the world.
The UN estimates the number of people living in medium-sized cities of up to 5 million inhabitants is expected to jump to 1.1 billion by 2030, up from 827 million in 2014.
It also predicts an estimated 27 percent of the world's population will be living in smaller cities of at least 1 million people by 2030.
Growth in the US has generally been slower, with the fastest increase happening in Charlotte and Austin, with 5 per cent and 4 per cent annual growth respectively.
Growth in also Europe is also markedly slower, with the majority of urban areas growing at less than 1 per cent each year.
This rapid urban growth can be extremely problematic.
Slum living, already forced on a third of the world's urban populations, will become even more widespread as cities became increasingly packed with people.
As a result billions could be at risk of hunger, thirst and appalling living conditions, creating tinderbox conditions that could ignite civil unrest and conflict.
Research published last year suggested the brunt of migration will be into smaller cities.
According to Eugene Zapata Garesche, Latin America and Caribbean director for the 100 Resilient Cities (100RC) initiative the cities that are set to grow the most are medium and small-sized ones.
'The cities that got prepared to grow are not growing anymore as they are already big enough. That is where the whole challenge of urbanisation is sitting today.'
As megacities such as Brazil's Sao Paulo can no longer sustain more population growth, cities like Curitiba or Salvador, which still have room to expand, will be required to absorb rising numbers of people, said Mr Zapata.
'You have cities like Mexico City that aren't even growing any more population-wise, because the city has turned into a nightmare for commuting, and there's a lot of pollution,' he said.
Making sure resilience is institutionalised by cities and supported by legislation is essential to guarantee the long-term continuation of the strategy, he said.
The biggest resilience challenges for cities are improving transport and waste management, and securing water supplies, along with social policy issues such as supporting migrants, he said.
In 2016 there were 512 cities with at least 1 million inhabitants globally and by 2030, 662 cities are projected to have at least 1 million residents.
In 2011, a report, entitled Popluation: One Planet, Too Many People? outlined the issues we might face if populations continue to grow.
It suggests that without drastic changes there will not be sufficient resources to provide people with basic human needs such as water, food, energy and shelter.
Climate change is likely to place even more stress on resources, resulting in as many as a billion people moving from inhospitable regions.
Water requirements are projected to rise by 30 per cent by 2030 while food resources will be stretched by a doubling of demand for agricultural produce by 2050.
Slum living, already forced on a third of the world's urban populations, will become even more widespread as cities became increasingly packed with people.
As a result billions could be at risk of hunger, thirst and appalling living conditions, creating tinderbox conditions that could ignite civil unrest and conflict.