Every day hundreds of people fly into El Alto, Bolivia. Circling to land, the passengers stare down on a vast, windblown city of unpainted brick houses and tin roofs, sitting on narrow streets and squares.

The most arresting aspect of El Alto is its churches, placed with precision like chess pieces on a grid. Dozens of them, each bright white or blue, punctuate the drab landscape.

The man behind these churches is a missionary priest from Germany named Sebastián Obermaier. But it turns out they are just the most visible part of his network of social projects.

Thirty-two years ago when Father Obermaier arrived in El Alto it was a town of 80,000 people growing on the high plains next to La Paz, Bolivia's de facto capital. Today El Alto has surpassed La Paz and is the second-largest city in Bolivia, a boiling pot of 1 million people.

"No one could imagine this," Obermaier says. "The city of La Paz is now a little thing compared with El Alto."

In Obermaier's early days there were precious few services for Bolivia's indigenous rural population – no health centers, little electricity or running water, few schools. When these people, mainly Aymara Indian subsistence farmers, migrated to El Alto, they lived the same way.

Few formally trained doctors or dentists lived in the city. Residents were cut off from the traditional healers in their villages. Infant and maternal mortality were high, and emergency medical care nearly nonexistent.

"For the first eight years I acted as a doctor, taking out teeth, delivering babies. Not because I knew how, but because I had to," he says.

Today, instead of pulling teeth himself, Obermaier has built a health center attached to his home church. For little or no cost, doctors provide basic medical and dental care.

Other projects in the works include a hospice; a shelter for victims of rape and sexual abuse; low-cost senior housing; and a center for treating patients with HIV, only the second such center in Bolivia.

Obermaier has organized teams to go into El Alto's schools to teach about the disease.

"We're struggling so this doesn't become a city with AIDS," he says.

His approach to AIDS prevention flies straight as an arrow. His health center's walls display large posters encouraging condom use and detailing how HIV transmission can be prevented.

"They're small things he's doing," says Dr. Silvia Villarroel, health director for CARE, the nongovernmental aid agency, "but he's covering needs of the people that the health system can't cover."

Obermaier has also built schools and churches – by a conservative estimate, 30 of each. But trying to pry the exact number of projects out of him is impossible. "I've never counted them and I never will," he declares.

Dr. Villarroel from CARE laughs when asked to estimate how many churches he has built. "He's the only one who knows," she says.

"When I came here I had a clear vision – I'm never going to build a church," Obermaier says. "We celebrated mass in my living room, in the open air. But the population grew, and I did what I never wanted to do: I built a church."

Once he started building, a new idea grabbed hold: Since El Alto would continue growing, churches should be built while there is still space to put one in every neighborhood.

Within 15 years El Alto will double in size to 2 million people, and 1.6 million of them will be Roman Catholics, mainly recent immigrants from the countryside, he says.

"They've lost their roots," Obermaier says of these new arrivals. "In the church, they find a spiritual home in a new culture, a mix between the country and the city."

That loss of roots can mean a slide into crime, alcoholism, or poverty. Indeed, some describe El Alto as Bolivia's biggest slum.

But Obermaier sees something else.

Gazing at a courtyard where people are loading building supplies onto trucks, he says, "From the outside, you see nothing, you think it's total poverty. But inside, they're working. El Alto is rich in work."

The city has also developed into a flash point where the politics of the poor manifests itself. In 2003 President Gonzalo Sánchez de Lozada sent the Army to break up protests against his gas export policy. Violence exploded.

"It was war, three days of war," Obermaier recalls. "I had an ambulance, and all day and night we drove people to the hospitals." At least 30 people in El Alto and 80 in the region died in that conflict. The president left office and fled to the United States soon after.

Obermaier's energy knows no end. He often sprints across his churchyard or tears around the city in a 1980s four-wheel-drive vehicle to say five masses a day, beeping and waving at everyone he passes.

Most people smile and wave back. But his work isn't always met with enthusiasm. He has clashed with Bolivian President Evo Morales over religious education in schools, and his energetic approach has caused conflicts.

Antonia Castro owns a small store in Obermaier's parish. As a longtime resident, she's been treated at the parish health center over the years. "He's helped us a lot, with schools, with churches," she says of Obermaier. "When he goes, we're going to miss him a lot."

To Obermaier the growing number of evangelical Protestants, which now make up about 20 percent of the population here, is not a threat. Nor is belief in Pachamama, the Earth Mother of Bolivia's indigenous Andean religion, which many of his parishioners mix with their Catholicism. "We're Bolivian Catholics, not Italian Catholics, not French Catholics," he says. "This is our way to feel the same thing."

Encouraging people to attend church is the reason behind building the churches. "If you have a church far away, three people come," he says. "If it's close, 300 people come."

Looking at El Alto's skyline, punctuated by spires, or driving past schools and health centers he's helped build, it's hard to believe how much one man has done.

Yet Obermaier says that he wants nothing more than to be left in peace, anonymous, to continue his work for the rest of his life.

"You shouldn't be interested in me, because I do the same as everyone else," he says. "I do what I can."

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