Most of us have never spent time in the world's poorest, most overcrowded urban areas. So it can be hard to understand what life is like for the people who live there.
On the Urban Survivors website, Doctors Without Borders/Médecins Sans Frontières (MSF) offers a virtual journey through seven of those areas, in Guatemala City, Tegucigalpa, Dhaka, Johannesburg, Karachi, Nairobi and Port-au-Prince.
MSF is running programs in all those places, and the site offers a close-up look at the challenges facing residents, from violence in Tegucigalpa, Honduras, to malnourishment in Dhaka, Bangladesh, to cholera outbreaks and sexual violence in Port-au-Prince, Haiti.
Check out their "photofilm" about life in the Martissant area of Port-au-Prince:
With a combination of still photographs, video, and interviews with residents, MSF workers and photographers, the site creates an often dark portrait of the hardships of life in an economically depressed area, while also showing the vibrancy of life there, with people crowding the streets and going about their business.
The site's main goal is to highlight "the critical humanitarian and medical needs" in areas where there's no solid medical infrastructure in place.
MSF says that in these areas, "inhabitants live in a state of constant vulnerability. Pervasive pollution and unhygienic living conditions breed diarrhoeal and respiratory diseases. Population density, the lack of proper sanitation, and the shortage of health facilities mean that severe weather or outbreaks such as cholera can have devastating effects."
And alongside sanitation problems, MSF also talks about the "underlying social, legal, political and economic factors that impact on the health of the urban poor and their ability to access adequate medical care."
The site also investigates the specific needs in different places.
For instance, in Port-au-Prince, Haiti, sexual violence is a daily reality, and MSF has a team of psychologists who work with women who've been attacked.
In Dark City in Johannesburg, MSF workers focus on medical screenings, counseling, HIV testing and referrals.
And in Dhaka, two healthcare centres are focused primarily on helping malnourished children and their mothers with a therapeutic feeding program.
If you have a little time to spare, the site is a great way to get informed about life on the ground in some of the world's most disadvantaged urban centres. It was created in collaboration with the NOOR photo agency and Darjeeling Productions.