On Saturday I went with 4 of my colleagues (Sharon, Evelyn, Jill and Hannah) to Dharavi. Dubbed the world's largest slum, Dharavi has the highest density of population. The word slum refers to the fact that the people own their own property and businesses (which they have largely built themselves) but that the land is owned by the government. Reality Tours, which does the walking tour, is a very sympathetic group and shows the dignity of the people who live there. They use the money from the tours to run a community centre to educate the young people and to set up sports teams.
You are not allowed to take photos in Dharavi itself - it's not respectful - but we were able to take a couple from the railway bridge on the way into Dharavi from Mahim station.
The first people to settle in Dharavi were pottery workers from Gujarat. There is still a large pottery area in the slum. Later they were joined by leather workers from Tamil Nadu. Most of the million plus residents of Dharavi are second generation - their parents were the ones who moved there. Rents here are very cheap, there is water and electricity, and transport is provided by the 2 mail railway lines on either side of the slum. There is an extremely large recycling industry in the slum, especially in recycled plastic which is made into plastic pellets.
Dharavi is the setting of the 2008 film Slumdog Millionaire. Some of the children who act in the movie are real residents of Dharavi.