It would be an exaggeration to claim that Frank Sinatra started an architectural movement in the California desert, but certainly his choice of a contemporary design over the Georgian mansion he originally preferred set a trend with international influence. Sinatra's architect, E Stewart Williams, who has died aged 95, vividly recalled the singer placing his order on May 1 1947. He walked into the Williams' family office in Palm Springs, the resort then popular with Hollywood stars, wearing a sailor's cap and sucking an ice cream. "I wanna house," he barked.
It was to be Williams' first commission, but to his alarm he realised that Sinatra wanted the building ready by Christmas for a party. To make matters worse, the singer favoured a Georgian mansion, a style hardly suitable in an arid, cactus-dotted valley where summer temperatures could reach 120F and exceeded 100F for weeks on end.
So Williams presented Sinatra with two drawings. One showed the Georgian design, the other a single-storey house with a "shed roof" - flat but slightly sloping - and long, horizontal lines, windows down to the ground, and framed not just with wood or brick, but steel and aluminium. It was a variation on the emerging style that became known, through Williams and his fellow regional architects such as Albert Frey and Richard Neutra, as desert modernism.
Today, because of buildings they and others erected there, Palm Springs is a focus of modernist architecture, with structures from the town hall to banks, public buildings and private homes displaying an inspirational style that, sadly, disappeared in the 1970s. Sinatra's was one of the first and remains one of the most famous.
Williams' drawings persuaded the singer to go modern, and the house on Alejo Road was finished in time for the party. As Stewart's architectural partner, his brother Roger, said: "I'm so glad. We'd have been ruined if we'd been forced to build Georgian in the desert." Sinatra's house was known as Twin Palms after the two trees that still stand beside it, and featured a swimming pool shaped like a grand piano. Williams always insisted this was accidental, but with the sun at a certain angle it even casts shadows that look like piano keys.
Sinatra lived in the property with his first wife Nancy and family, and then with his second wife, Ava Gardner. In the late afternoons he would hoist a flag bearing the Jack Daniels whiskey logo to signal to neighbours that it was cocktail time. He stayed there for 10 years.
After divorcing Gardner, he lived in nearby Rancho Mirage until shortly before he died, occupying a huge compound and an architectually less distinguished property.
Williams' style was influenced by a 1930s trip to Scandinavia, which gave him an affinity for simplicity - and introduced him to his wife of 60 years, Mari, who died in 1998. "His modernism took the international style and warmed it up," explained Peter Moruzzi, an architectural historian and founding president of a Palm Springs society of preservationists. "Stewart combined contemporary, or modern, with natural materials in a sublime way."
In a 50-year career, Williams dotted Palm Springs and the surrounding Coachella Valley region with numerous works. Many survive, but some were demolished before the area belatedly awoke to its architectural heritage. Half a century after completing the Sinatra house, Williams came out of retirement to expand the Palm Springs Desert Museum he had designed in 1976.
The main building is sheathed in volcanic cinder, cantilevered over a sunken sculpture garden. His other projects included the graceful Edris residence on a hill surrounded by native plants; a 1956 home for his own family, with a V-shaped roof that created shelter for outdoor living and a garden that spilled into the living room; the upper station of the Palm Springs Aerial Tramway; and several bank buildings that make the casual visitor stop and stare.
Williams was born in Dayton, Ohio, the son of a well-known architect, Harry Williams, who when he received a commission in Palm Springs liked it so much he stayed. Stewart studied architecture at Cornell University and took a master's degree in 1934 at the University of Pennsylvania. He taught for several years at Bard College, New York, and studied such modernist architectural masters as Mies van der Rohe and Walter Gropius.
After returning from his Scandinavian tour, Williams worked for architect Raymond Loewy, who assigned him to the 1939 New York World's Fair. By 1943, he was designing ships for the US navy, and after the second world war he joined his father in Palm Springs.
He is survived by his daughter and two sons.
· Ernest Stewart Williams, architect, born November 15 1909; died September 10 2005