I stumbled across an interesting article on noted actressRachel Weisz. Of note:

Once she won the part [in The Constant Gardner] , she was off to Nairobi, Kenya, and its Kibera slum, the largest slum in sub-Saharan Africa, with more than one million inhabitants. Lake Magadi, with its flock of pink flamingos, is where the cast and crew lived in tents, as there were no hotels, no cities, nothing but open spaces … and need. She became immersed not only in the fictional story, but the sad facts of the country in desperate need. She had visited Kenya many years before as a tourist. This time, however, filming in the Nairobi slum, she underwent a transformation that is prevalent on the screen. She’d never seen poverty on such a massive level. But like her character, who felt most comfortable in the slum, where she could help people, Weisz says she felt most relaxed there, too. Then, it was on to Loiyangalani, where Samburu tribes have lived for thousands of years. It was a region with great beauty, but little facilities, especially for education.
True to the film’s spirit of activism, an idea was born.
“When we were filming in the shanty town, rather than give money as a location fee, we actually built things in the slum. We built a bridge, fresh water tanks, and restroom facilities, because there was no running water there and there was a badly needed bridge to access one side to the other. So it was kind of about giving back to the community in a really helpful way.”
…The reality of the situation they’d left behind in Kenya, however, haunted the cast and crew long after filming wrapped. Just as the film was about something, they felt they had to do something.
“The shanty town wasn’t a set. It was a place where we went with a tiny crew, like a documentary. We didn’t dress people in the background in costumes. We interacted with reality.” The film’s producer, Simon Channing-Williams, told his cast he thought the help should continue after the film wrapped. “And we all just said, ‘Yes.’ That was the spirit in the film. That was what the film is really about.”
The Constant Gardener Trust was formed, and helps in various ways. So far, the trust has helped build high-school-level educational facilities. “In Loiyangalani in the north, an area where there are no high schools,” says Weisz, “when they hit 11, that was it, their education is over. So we committed to it; Ralph Fiennes, myself, the producer, the director, John le Carré (who wrote the novel), and John Lyons (from Focus, the production company). We are all part of a trust and we raise money, being able to build a new classroom each year so that class can move up. So I come up with these fundraisers in New York. For instance, Cartier just recently did a big fundraiser and they gave me a huge amount of money.”

Applause.