When Sister Conchita McDonnell was a young missionary, preparing to head off to Africa for the first time, another one of the Sisters of the Holy Rosary gave her some advice: work with the goal of putting yourself out of business.

The idea was to build a school, or a hospital, or something else that could help the local people, and then leave it to the locals.

Sister Conchita and the other Killeshandra Nuns, as the missionary sisters are known, did their jobs well. Maybe too well. Actually, definitely too well.

Since they were founded in a small town in County Cavan in Ireland 90 years ago, the Missionary Sisters of the Holy Rosary built more than 200 elementary schools and more than 40 high schools, graduating more than 75,000 children in nine countries throughout Africa.

They built 32 hospitals.

They survived war, disease, and famine.

They gave away everything — their money, their food, their youth, their retirement funds. They returned from Africa, in their 70s and 80s and 90s, and had nowhere to live.

The plight of the Killeshandra Nuns raises the question: what do we owe missionaries who forfeit their own financial well-being for the poorest of the poor?

Paul Maguire and Liam Hegarty, a pair of Philadelphia-area businessmen, and many others who are big fans of the missionary sisters, decided they owed the Killeshandra Nuns a retirement home.

The Philly connection is not by accident. The Delaware Valley has always been linked to the sisters. One of the congregation’s founders, Sister Philomena Fox, was from the Philly area, and the current leader of the congregation, Sister Maureen O’Malley, went to Archbishop Prendergast High in Upper Darby.

In August, Shanahan House opened in Dublin. Named for Bishop Joseph Shanahan, who founded the Holy Rosary Sisters congregation in 1924, the home was purposely built for the aging demographic of the returning Killeshandra Nuns. Now people like Maguire and Hegarty are helping the nuns come up with the $4 million it cost to build Shanahan House.

They hope to raise $2.5 million in the United States and $1.5 million in Ireland.

“None of us wanted to come home. We all expected we’d die in Africa and be buried there,” Sister Conchita explained over a cup of tea at the Starbucks on Beacon Street across from Boston Common. “In the last 15 years, many have come home.”

She said about 170 nuns between the ages of 86 and 97 have returned over the past decade alone.

The places where the Killeshandra Nuns have worked over the past 90 years, beginning in Nigeria, read like a map through the developing world: Sierra Leone, Liberia, Ghana, Cameroon, Ethiopia, Kenya, Zambia, South Africa, Brazil, Mexico.

During Sierra Leone’s long civil war, the nuns spent nine years in the bush with refugees.

“We’re the Green Berets in habits,” Sister Conchita said.

She isn’t kidding. Once, when she was teaching the Igbo people in the south of Nigeria, another of the Killeshandra Nuns, Sister Monica Devine, was working with the neighboring Tiv people. When the Igbo and Tiv people went to war with each other, the nuns found themselves in opposing camps. The Igbo elders assured Sister Conchita they would protect her as one of their own.

Sister Mary Mullin, who worked in Liberia, returned to Ireland in June and can’t get back there because of the Ebola epidemic. She’s desperate to get back. Other Killeshandra Nuns are still in Liberia, helping those stricken with Ebola.

About 10 years ago, the Killeshandra Nuns realized they had given away everything they had, and that they had no place to live in retirement. Other communities and congregations accomodated them temporarily. In the heady days of the Celtic Tiger, Ireland’s booming economy, there was talk of a retirement home being built for them. But the economy crashed and so did all that talk. Then came Shanahan House, and a $4 million debt.

Sister Conchita survived war and life-threatening diseases, but she says coming up with $4 million is the biggest challenge she has ever faced. Like most missionaries, she’s very good at giving, but is intuitively wary of taking.

“We’ve done fundraising before, but it was for the missions, not ourselves,” she said.

With the help of Maguire, Hegarty, and a legion of fans, the nuns hope to raise awareness and funds in Boston, New York, Philadelphia, Pittsburgh, Chicago, and Cleveland, among other places.

One of the Killeshandra Nuns, Sister Edith, was 90 when she reluctantly returned to Dublin from Nigeria. She was in a nursing home for four years before she died recently. When they opened Sister Edith’s purse after she died, they found an open-ended return plane ticket to Lagos.

“She was always going back,” Sister Conchita said. “Always.”

To donate to the Killeshandra Nuns’ retirement home, visit their donation page.