Gregory Ain, a midcentury champion of modern architecture whose students included Frank Gehry, is virtually unknown outside Los Angeles today. His left-leaning politics made him the object of decades-long F.B.I. surveillance and McCarthy-era witch hunts that took their toll on his career and legacy.

Even the fate of his most important commission — an exhibition house in the garden of the Museum of Modern Art — is a mystery. It is now the subject of “This Future Has a Past,” an installation at the Center for Architecture in Greenwich Village.

J. Edgar Hoover once called Ain (1908-88) the most dangerous architect in America. His body of work includes many homes in and around Los Angeles, as well as Community Homes Cooperative, an unrealized housing development from the 1940s that caught the attention of F.B.I. informants who said the project had ties to the Communist Party.

While under surveillance, in 1950, Ain designed a house for MoMA, during an era when the museum commissioned exhibition houses designed to bring architecture to a mass audience. Philip Johnson, director of the museum’s department of architecture and design at the time, enlisted Marcel Breuer for the first one in 1949.


“People would talk about Gregory Ain in a very fond way, but would never go past a certain point,” Ms. Robbins, who is working on a documentary about Ain, said. “It was as if there was a wall that would come down.”

In part because of his tarnished reputation, Ain received few commissions after the MoMA exhibition house in 1950. It also didn’t help that many of Ain’s friends and clients lost work because of anti-communist hysteria. They included Dalton Trumbo, the blacklisted screenwriter of “Roman Holiday”; Frank Wilkinson, an activist who was incarcerated; and Ben Margolis, a defense attorney for the Hollywood Ten, artists who were punished for refusing to testify before the House Un-American Activities Committee. ... Still, the fate of Ain’s MoMA house remains a mystery. Even letters in the museum’s archive offer no conclusive resolution.

“The archives go dead on two topics: They don’t tell you if someone came to the rescue of this house, and if they didn’t, there’s no documentation that it was destroyed,” Mr. Bergdoll said. “There is correspondence with many people interested in buying the house, and then each thread fizzles out, and then the correspondence fizzles out altogether.”