His signature glasses—he hasn't changed styles in 50 years—conceal a tiny hearing aid these days, and most nights he's in bed by 10. But at 77 Philip Johnson has lost neither the spunk nor the acerbic wit that has made him architecture's grand old man—while remaining its perennial enfant terrible. Architects are "just as jealous and small-minded as sopranos," he admits, and the lecturer in him can rarely resist the chance to sound off. "Hearing an audience react," he says, "rouses me more than sex or liquor."

Still, Johnson, who was architecture's bad boy far longer than he has been its elder statesman, figures the main reason for the acclaim is that "I have outlived the competition." In truth, it is ingenuity, not mere longevity, that has made him urban America's chief form giver. In his eighth decade, Johnson stopped building the unadorned glass boxes that, since his 1932 exhibition of the International Style at Manhattan's Museum of Modern Art, had defined the 20th century's most popular architectural form. Calling his earlier handiwork "wrong, simply wrong," he turned instead to buildings lavishly decorated with details culled from architecture's past. The most prominent is his firm's New York headquarters for AT&T, a $200 million, pink granite-sheathed skyscraper topped off with a classical broken pediment reminiscent of the top of a Chippendale highboy.

When plans for the building were unveiled in 1978, one critic called it "the world's tallest grandfather clock." But now, as the building nears completion, it is becoming one of the most admired on the New York skyline. More important, it has emerged as the symbol of a new architecture labeled "post-modernism" because it rejects modernism's glass boxes. With his partner, John Burgee, 50, Johnson, the guru of the movement, is currently working on 10 buildings, each worth more than $100 million. One resembles a Gothic cathedral, another a Dutch renaissance town hall.

Not everyone applauds. Some observers label his work a "pastiche," and students at the University of Houston are protesting his plans for their architecture building, which even Johnson admits he copied from an 18th-century French designer. "What's wrong with copying?" asks Johnson archly. Then he mockingly announces, "I guess I can't be a great architect. Great architects have a recognizable style. But if every building I did were the same," he adds, "it would be pretty boring."

Johnson has never been that. The son of a wealthy Midwestern lawyer, he took seven years to graduate from Harvard, then traveled the world and dabbled in fascist politics before becoming an architect at 40. Though he gradually won prestigious commissions, his earliest client was himself. In 1949 he built, on a 32-acre hillside in Connecticut, his famous Glass House, a simple rectangle in which he still spends every weekend. Weekdays, he lives in a small apartment with a panoramic view including AT&T, his Museum of Modern Art sculpture garden and his most famous "modern" skyscraper (designed with Mies van der Rohe), the Seagram Building.

It's not a view he totally enjoys. Like a movie star who winces at seeing himself on-screen, Johnson says, "There's no worse feeling than seeing my buildings and realizing the mistakes." But instead of being regretful, Johnson says, "I just make sure my next building is better."