Architect Robert Venturi in 1991. (George Widman/AP)

Robert Venturi, an iconoclastic architect often considered the father of postmodernism who rejected sterile, glass-cube structures in favor of an inclusive, eclectic style that embraced community values and a touch of vulgarity, died Sept. 18 at his home in Philadelphia. He was 93.

His death was announced by VSBA Architects & Planners, the firm he started with his wife, Denise Scott Brown. He reportedly had Alzheimer’s disease.

Mr. Venturi first gained acclaim as a theoretician and writer with his 1966 book, “Complexity and Contradiction in Architecture,” in which he turned Mies van der Rohe’s famous dictum about simplicity in design — “Less is more” — upside down, cheekily declaring, “Less is a bore.”

Over time, Mr. Venturi went from renegade to revered master and in 1991 received the Pritzker Architecture Prize, often equated to the field’s Nobel Prize.

“He has shaped a generation of architects, and more than any other figure has brought architecture to its present moment,” New York Times architecture critic Paul Goldberger wrote at the time. “It is impossible to imagine the world of architecture in the last 20 years without Robert Venturi.”

Mr. Venturi’s declaration of architectural values, “Complexity and Contradiction,” was a manifesto that took aim at the prevailing modernist notion that architecture should aspire to a cold, glassy perfection with cold, glassy buildings.

A 2,000-square foot beach house designed in the 1960s by Robert Venturi. (Mel Evans/AP)

He argued instead that architecture should reflect changing times and social needs. The world of design, he said, had too long been in the grip of the dogma that architects were godlike creators who could impose their vision on the landscape.

Mr. Venturi advocated a people-first architecture drawn from local customs, historical context, vernacular buildings and popular taste — including bad taste.

“Architects can no longer afford to be intimidated by the puritanically moral language of orthodox modern architecture,” he wrote. “I like elements which are hybrid rather than ‘pure,’ compromising rather than ‘clear,’ distorted rather than ‘straightforward.’ . . . I am for messy vitality over obvious unity. . . . I am for richness of meaning rather than clarity of meaning.”

His views, which echoed the pop art concepts of Jasper Johns and Robert Rauschenberg, were seen as radical and incited rage among the architectural establishment.

“The profession is split right down the middle — 90 percent against,” critic Ada Louise Huxtable wrote in the Times.

But to many, including Yale University professor Vincent Scully, Mr. Venturi was a visionary whose book constituted “probably the most important writing on the making of architecture” since Le Corbusier in the 1920s.

As an unexpected encore to “Complexity and Contradiction,” Mr. Venturi journeyed to Las Vegas, where he and his wife invited several of their Yale students to take the measure of the place. He wasn’t interested in gambling — he spent a total of $1.05 on slot machines — but went there to study the buildings, signs and roads in what may be America’s most garishly self-indulgent city.

In their 1972 book, “Learning From Las Vegas,” written with architect Steven Izenour, Mr. Venturi and Scott Brown analyzed the physical layout of the city, as if conducting an archaeological reconstruction of a Roman ruin.

They mapped the scale and distribution of stores, car rental offices, casinos and wedding chapels and even calculated the intensity of lighting from the city’s ubiquitous flashing signs. Las Vegas wasn’t just a neon-lit den of vulgarity, they concluded. It was a prime example of a city built to accommodate the automobile. As a result, signs were often more important than the buildings they loomed over.

“In the landscape of the automobile, the architecture becomes insignificant, a pimple on the landscape of parking lots,” Mr. Venturi told the Times in 1971. “The lesson of Las Vegas is that in order to be read in that context architecture cannot be a refined, detailed form to be savored as you walk by it at three miles an hour. It must be symbolic, not pure, if it is to be read at 70 miles an hour.”

Some of his fellow architects thought Mr. Venturi was joking or — as one colleague put it — in thrall to “the most barren, mindless examples of mid-cult America.”

Undaunted, Mr. Venturi began to put his ideas into practice. His first important building, completed in the early 1960s, was the Vanna Venturi House, which he designed for his mother in Philadelphia.

It is recognizable as a traditional house, but instead of connecting the roof above the front door, Mr. Venturi left the gable open at the top. He painted the exterior a pale green because he was told no house should be painted green. An interior staircase is wide at the bottom, then narrows toward the top, as the public living space is left behind for the private bedrooms above. (The house was featured on a U.S. postage stamp in 2005.)

Mr. Venturi was hardly snobbish about his work and often took on humble assignments, designing fire stations, retirement homes and warehouses. “Ugly and ordinary is better than heroic and original,” he said.

As his reputation grew and his views became more mainstream, his commissions became more prestigious. In the 1970s, he designed Freedom Plaza, a raised granite and marble surface along Pennsylvania Avenue NW, in Washington.

He later designed campus buildings for Harvard, Yale and his alma mater, Princeton University, and created a celebrated addition to the Oberlin College art museum in Ohio. In 1991, he completed two ambitious projects — an addition to the National Gallery in London, known as the Sainsbury Wing, and a new art museum in Seattle.

His eclectic approach made it difficult for critics to identify a signature style, but in general Mr. Venturi preferred stone and masonry to glass. He designed with a consciousness of the past, if only to depart from it. He liked billboard-size signs and often had giant letters carved into his facades, including at the Seattle Art Museum. He used colors, patterns and textures in unexpected ways and saw no reason the back of a building should look the same as the front.

In matching a structure to its surroundings, he incorporated a sense of rhythm in its visual elements, which he likened to jazz. He placed windows at irregular intervals, creating dramatic interior lighting.

Mr. Venturi often referred to his work as creating “decorated sheds,” or basic structures enlivened with ornamentation and symbols. His influence came to be seen in hundreds of new buildings, as younger architects freely incorporated the historical references and other postmodern elements that Mr. Venturi had introduced.

But he steadfastly refused to take up the crown as the progenitor of an architectural movement.

“I am not now and never have been,” he said in 2001, “a postmodernist.”

Robert Charles Venturi Jr. was born June 25, 1925, in Philadelphia. His father ran a wholesale fruit business, and his mother was a socialist and feminist. Raised as a Quaker, Mr. Venturi was a conscientious objector during World War II.

He graduated from Princeton in 1947 and received a master’s degree from Princeton’s architecture school in 1950. He then joined the architectural office of Eero Saarinen before winning a fellowship and moving to Rome in 1954.

For two years, he studied architecture, urban design and the movement of people through the streets. He developed a respect for imperfection, observing that the excitement of city life often grew out of unexpected corners, shapes and encounters that created harmony or tension.

After returning to Philadelphia, Mr. Venturi worked for architect Louis Kahn, then taught at the University of Pennsylvania from 1957 to 1965 and at Yale from 1966 to 1970.

During those years, Mr. Venturi supplemented his income from the family’s produce business, which he managed as president until 1973.

In 1967, he married Scott Brown, who had been a colleague at the University of Pennsylvania. They collaborated on design and writing projects, and both were upset when the Pritzker Prize was awarded solely to Mr. Venturi. In 2002, they received the Vincent Scully Prize at the National Building Museum for their joint contributions to architecture.

Mr. Venturi’s survivors include his wife and a son, James Venturi, an urban planner.

In addition to buildings and public spaces, Mr. Venturi designed furniture and table ware and remained active well into his 80s. He never lost his disdain for what he considered the soulless architecture of his modernist predecessors, who often designed glass-box buildings with walls of windows, “but you would never have a wall with a window in it.”

Instead, Mr. Venturi wrote in “Complexity and Contradiction in Architecture,” he drew inspiration from the “everyday landscape, vulgar and disdained,” which was “valid and vital for our architecture as a whole.”