Before the spies came, the house was perfect.

Five thousand square feet, wide windows, a grand staircase, a front porch with a panoramic view of nature. The year was 1933, and Northern Virginia was still the countryside, even with Washington just across the Potomac. So it was the ideal retreat for Florence Thorne and Margaret Scattergood, two pioneers of the American labor movement who defied the gender expectations of their time.

“Florence said, ‘Of all the houses we looked at, this is the only one I would care to live in,’ ” Scattergood recalled years later. “That was pretty final.”

The women lived at the estate for a decade before it appeared that some federal agencies were also looking to buy property across the Potomac. And they wanted the land where the big white house sat.

In 1948, Thorne, 71, and Scattergood, 54, made a deal: They would sell their 30 acres to the government, but only if they could live out the rest of their lives in their home. Any agency that acquired the land would have to abide by that agreement.

And that was how two rebellious ladies came to live on the grounds of the Central Intelligence Agency for nearly 40 years.

In the late 1950s, the CIA took over the land in Langley, Va., to build a headquarters that could accommodate its fast-growing operations. It kept growing, getting closer and closer to Scattergood and Thorne’s house but allowing them to keep their own entrance. The women were affectionately known at the CIA as “the sisters,” even though they weren’t related.

A census record lists Scattergood as Thorne’s “partner.” If that partnership included romance, it was a well-kept secret. Scattergood was a devoted Quaker, and Thorne was a Baptist-turned-Catholic. Scattergood’s family members, who have diligently kept records of her life, say the pair had separate bedrooms and never acknowledged a relationship beyond friendship.

“That was always the question,” said Meg Blanchet, a great-great-grandniece of “Aunt Marge.”

When the pair first met, Scattergood was looking for a job. Like Thorne, she’d graduated college before women even had the right to vote. She volunteered to do aid work in France during World War I, driving across the country and back in a Model T Ford. When she was 32, a friend told her about a woman in Washington who was involved in the movement for workers’ rights.

“She’s no bigger than a wisp of dust you might find under the bed,” her friend said. “I think she’s doing three men’s work, and I think she could use some help.”

Decades later, Scattergood recalled in an interview what it was like to meet Thorne, who had worked for American Federation of Labor leader Samuel Gompers, wrote his biography and would come to run the AFL’s entire research operation.

“It was on the 16th of April in 1926. I can remember the date, very important one for me,” Scattergood said. “Florence Thorne was a very interesting person. She was a slender, little slight lady, and very gentle.”

At their Virginia home, the women hosted family weddings, filled the attic with books and antiques from around the world and admired the view from their front porch.

At work, they empowered unions across the country to fight for better working conditions by keeping unemployment statistics and researching the companies that labor leaders were considering striking against. These covert investigations showed whether a company could survive a strike without shuttering and, if so, just how much they were shortchanging their workers.

All the while, investigations of a different kind were taking place next door to Scattergood and Thorne’s home.

CIA historians say Thorne was amenable to her neighbors; she asked them to kindly expedite her visas when she traveled overseas. But after she died in 1973, at the age of 95, it was just Scattergood at the big white house.

In her eyes, the agency was an affront to her values. After retiring from the AFL, Scattergood dedicated herself to civil rights. She’d written to Martin Luther King Jr., funded affordable housing efforts in the District and fought swimming pool segregation in Virginia. She was also a staunch pacifist, and as the CIA grew, she lobbied Congress to reduce the budget of the U.S. military and intelligence operations.

“I remember her saying the one thing she’d like to do is stop World War III. She had small aspirations, you know,” said Sylvia Blanchet, another great-great grandniece.

In the late 1970s, Blanchet and her husband moved into the property’s guesthouse. Their son was born there, and the placenta was buried on the property. With their aunt, they attended the Langley Hill Quakers meeting just down the street. When the group got involved in the sanctuary movement, which helped Central American refugees flee into the United States in the 1980s, their family did, too.

Soon, Scattergood was having the refugees over for dinner. Some stayed in her guest room.

Blanchet remembers them as students, families and “just ordinary people who had really suffered because of the war,” mostly from El Salvador and Guatemala.

The CIA believed the visitors were Sandinistas, a leftist resistance group the CIA was working against in Nicaragua. Sometimes, they ended up at the gate of the CIA when they were looking for Scattergood’s house. Officials now say they are not sure whether the visitors were indeed rebels.

Despite the tension over worldviews, Scattergood invited officers into her home. She saw them on her nightly walks around the perimeter of her land, which she took even after she needed a cane to get around. Deputy Director Harry Fitzwater instructed security officers to check on Scattergood as part of their nightly patrols. He sent her turkeys and hams for the holidays.

In 1984, Scattergood accepted an invitation to be the guest of honor at a luncheon with the agency’s top brass, including Director William Casey, who would later come under investigation for the CIA’s actions opposing Sandinistas in Nicaragua. Blanchet accompanied her aunt. She remembers the men asking Scattergood about her role in the AFL. She explained that her aunt was “like the CIA of the labor union.”

“There was this silence at the table,” Blanchet said.

Two years later, Scattergood died at 92. She spent her final weeks singing with members of her Quakers meeting and reading works such as “The Central American War: A Guide to U.S. Military Buildup” and “The Bulletin of the Atomic Scientists.”

She bequeathed the antiques she and Thorne acquired to their family members. Her body was donated to medical science. And her house, as promised, went to the CIA.

For 15 years, the CIA’s security team used the manor as a literal doghouse, a place to keep their K-9 unit. They trained the dogs on the grounds where, one CIA official suspects, the bomb-sniffing hounds found the buried placenta. CIA employees brought their motorbikes into the house for maintenance and used the grand foyer for storage. Eventually, the house seemed to be in such disrepair that it was slated to be demolished.

But an employee who loved the old home, and who got an inspector to confirm it was structurally sound, intervened. In the early 2000s, it was completely renovated into the Scattergood-Thorne Conference Center, a place for educational conferences, team-building retreats and the occasional soiree.

It has an industrial kitchen for catering events, conference tables in each bedroom, a small satellite dish on the roof and TVs on the walls — fixtures far removed from its historical heart. And yet, the layout of the conference center still feels like a house. Most of the furniture is antique, and the shelves are filled with curios from foreign officials and books with names like “Cyberspies” and “Mobilizing Women for War.” The grand staircase wows visitors. Although there are paved roads and other buildings nearby, the house is surrounded by trees.

“You forget you’re at the CIA when you’re out here,” said Janelle Neises, deputy director of the CIA Museum whose job description once included readying the house for events. When there were brief moments of calm, Neises said she would venture to her favorite place in the house: the porch, with its view of the old trees that remain and two rocking chairs.

Read more Retropolis: