Robert Venturi, the influential American architect and theorist whose buildings and best-selling books helped inspire the movement known as postmodernism, in which historic elements enliven contemporary forms, died on Tuesday September 18 2018 at his home in Philadelphia. He was 93. Robert Charles Venturi Jr. was born in Philadelphia on June 25, 1925. His father ran a produce business; his mother, Vanna (Luizi) Venturi, was active in socialist and feminist circles. Robert, their only child, attended the Episcopal Academy in Merion, Pa., and then enrolled at Princeton University. Raised as a Quaker, he said he registered as a conscientious objector during World War II. Mr. Venturi arrived at Princeton in 1944, when modernism had taken root at other architecture schools, particularly Harvard’s, then led by the Bauhaus master Walter Gropius. After receiving his undergraduate and graduate degrees from Princeton, he worked for Eero Saarinen and Louis Kahn , modernists with iconoclastic streaks, before winning a fellowship at the American Academy in Rome. He spent two years in Europe. Mr. Venturi joined the faculty at the University of Pennsylvania, where he met Ms. Scott Brown, an urban planner who was also teaching at Penn and who had recently been widowed. They married in 1967. Mr. Venturi went into private practice in 1960, first in partnership with William H. Short and then, starting in 1964, with John Rauch. Ms. Scott Brown joined the Venturi Rauch firm in 1969 as partner in charge of planning. In 1989, when Mr. Rauch resigned, the firm was renamed Venturi, Scott Brown & Associates. At its peak it employed nearly 100 people. It is now known as VSBA Architects & Planners. Mr. Venturi won the Pritzker Prize, considered architecture’s highest honor, in 1991. In addition to his son son, James Venturi — who said his father was listening to Beethoven’s piano sonatas when he died — Mr. Venturi is survived by Ms. Scott Brown.