Even casual fans of Frank Lloyd Wright’s architecture are familiar with the Guggenheim Museum’s spiral ramp, which wraps around a six-story atrium. Wright designed the Guggenheim in 1943, though it didn’t open until 1959, shortly after the architect’s death. But the New York museum’s famous spiral inspired a little-known house that Wright designed for his son David in the Arcadia neighborhood of Phoenix. Preservationists say the house could be torn down if a new buyer isn’t found soon.

“We don’t have a lot of time,” says Janet Halstead, executive director of the Chicago-based Frank Lloyd Wright Building Conservancy, which is devoted to the preservation of Wright’s remaining structures. For 40 years, she says, no Wright structure has been demolished, though several have been lost to fire or weather.

Completed in 1952, the house is made of concrete blocks and features an exterior spiral ramp that leads to the second-level entrance. “It’s the only Wright house with a spiral,” says David De Long, professor emeritus of architecture at the University of Pennsylvania and the author of several books about Wright. “It’s really a very important design, one of the best of Wright’s late career."

Earlier this year, a Phoenix development company, 8081 Meridian—which, according to its website, specializes in “custom luxury homes”—bought the house for $1.8 million and filed an application with the city to split the 2-acre property into two lots. That alarmed preservationists, who feared the house could be demolished to make way for the usual McMansions. John Hoffman, co-owner of 8081 Meridian, now says he and his business partner had hoped to move the house, perhaps to Taliesin West, Wright’s winter home and school, in nearby Scottsdale.

In June, the conservancy—along with the National Trust for Historic Preservation, AIA Arizona, and several other organizations—asked the Phoenix Planning Commission to consider historic preservation and landmark status for the house. The commission agreed to initiate the designation process, which will require a vote from city council. (That could happen in November.) But even if the house is granted landmark status, it could still be torn down. Meanwhile, development plans, including demolition, are on automatic hold.

That gives the conservancy a window of time to find a new buyer. “We’re doing everything we can to reach out to potential buyers,” Halstead says. “It’s a tall order, though, to find someone willing to buy the house in order to preserve it.” However, the conservancy has a good record of saving threatened Wright houses by convincing preservation-minded buyers to step in as white knights.

Hoffman says he and his partner are willing to sell the house and property intact or divide the lot in such a way that they could sell the Wright house (for a “bargain price” of less than $1 million, he says) but still build two homes on the remaining land. “Or,” he says, “we will proceed with our original development plan.”