It’s hard to say which is more startling. That a developer in Phoenix could threaten — by Thursday, no less — to knock down a 1952 house designed by Frank Lloyd Wright. Or that the house has until now slipped under the radar, escaping the attention of most architectural historians, even though it is one of Wright’s great works, a spiral home for his son David.

The prospect of its demolition has suddenly galvanized preservationists, as these crises often belatedly do. They are pursuing a two-pronged attack, trying to have the building designated a landmark, although in Arizona, where private property rights are strong, landmark status is really just a stay of execution, limited to three years. After that the owner is free to tear down the place. So the other prong of attack is to find some preservation-minded angel with deep pockets who will buy it from the developer. Preferably today.

Wright designed this 2,500-square-foot concrete home for David and his wife, Gladys, on a desert site facing north toward Camelback Mountain in a neighborhood called Arcadia. The area, known since the 1920s for its citrus groves and romantic getaway resorts among old Spanish colonial and adobe revival homes, was increasingly subdivided after the war and filled with new, custom-designed ranch houses.

But the Wright lot still had its orange trees. The architect took advantage of them by raising his son’s house on columns, to provide views over the orchard. It was a touch that partly echoed Le Corbusier’s famous Villa Savoye in France; at the same time Wright chose a spiral design akin to the Guggenheim Museum’s. He had drawn plans for the Guggenheim by then, but it was still some years away from construction.