*NEW: Our new in-depth interactive feature takes you to each of them - to Mumbai, Cape Town, Mexico City, Nairobi, and Karachi - to give a new perspective on the informal slum cities where one quarter of the world's urban population live.*
This week - in the lead up to the historic United Nations Habitat III conference on housing a development in Quito, Ecuador - PLACE is publishing a five-part package of stories featuring exclusive drone photography, interviews, and reportage from the world's five biggest slums. Watch the new trailer below.
Go here to see Kibera by drone, get a 360-degree view of the "Lunatic Express Railway", and meet the pupils of Egesa Children's Centre.
What's a slum?
"People think of slums as places of static despair as depicted in films such as 'Slumdog Millionaire'," says Sanjeev Sanyal, an economist and writer.
"If one looks past the open drains and plastic sheets, one will see that slums are ecosystems buzzing with activity," he said.
We report from Dharavi, Mumbai, where Slumdog Millionaire was filmed. Today it is home to a thriving economy with an estimated worth of $1 billion.
Siphesihle Mbango was just six years old when her friend, Asenathi, begged her to go with her to the toilet then ran outside alone - and was never seen again.
Through her story, we learn the dreadful human cost of a lack of adequate sanitation for residents of a Cape Town slum.
In Pakistan's Orangi Town, home to an estimated 2.4 million people, residents have given up waiting for the government to instal public services - and built them by hand.
Now more than 90 percent of the slum's nearly 8,000 streets and lanes have sewer pipes. We learn from the locals who have taken charge.
It's the future of urbanization, experts say. Ciudad Neza, now home to 1.2 million people, is an example of how slums - rather than being bulldozed - can be supported and upgraded to create thriving suburbs.
High levels of crime remain and public services are lacking, but Neza is a rising community where people say they're proud to live.