The place was France, and the time was summer, precisely a half-century ago. Two years earlier, the French had enjoyed the euphoria of liberation from the Nazi Occupation. And in the summer of 1946 another kind of liberation took place along the beache s of the Mediterranean: a few daring young women with ooh-la-la figures were wearing a new type of bathing suit that showed more than had ever been seen before in public. The tiny suit was named the bikini, in honor of the tiny Pacific atoll where the U.S . was testing atom bombs. The island's minuscule namesake set off its own beach explosions, and the aftershocks are still being felt.

Designer Louis Reard, a onetime engineer with Renault, the car company, had been turning out modest knit bathing suits since 1925, but in 1946 he realized that with the return of peace, people would want to start enjoying themselves again. "Rememb er that no one had been to the beach in years," points out Jamie Samet, fashion writer for the French daily Le Figaro. "People were craving the simple pleasures of the sea and the sun. For women, wearing a bikini signaled a kind of second libera tion. There was really nothing sexual about this. It was instead a celebration of freedom and a return to the joys in life."

Reard unveiled his design at a popular swimming pool in Paris, the Piscine Molitor, on the dazzling form of show girl Micheline Bernardini from the Casino de Paris. Soon the bikini was causing international incidents. France's Mediterranean neighbors r eacted as if some pestilence were spreading. Italy and Spain forbade bikinis on their beaches. At some Spanish resorts tourists who flouted the law would be sternly escorted back to their hotels by Civil Guard.

Prudish Americans initially rejected the bikini outright, preferring the molded-to-form, glamorous concoctions made famous in the films of Esther Williams. A May 1954 Vogue extolled one swimsuit style with its own little jacket as "still another way of looking dressed, not undressed." The architectonic American swimsuits with built-in shape were to beachwear what postwar fancy-finned luxury cars were to automotive design. There were also two-piece bathing suits with halter tops and shorts; t he midriff got a few inches of exposure, but the navel was decently concealed. The bikini, notes U.S. culture critic Anne Hollander, made a "charming appearance on the scene that went in the direction people were moving."

Beach by beach and body by body, the four triangles of fabric and odd bit of string became a style that women wore and men adored. The 50-year history of the bikini in many ways is a 50-year history of the uncloaking of Western mores, and the images it generated always stayed in the mind's--or libido's--eye. Click through the slides of memory:

--Demure and sexy at the same time, Brigitte Bardot at 21 stunned in a gingham bikini in the movie And God Created Woman.

--Britain's darling Diana Dors outdid herself in a Reard mink-kini at Cannes, making the film festival thereafter a favored search-and-display undertaking for starlets.

--Male moviegoers flocked to bond in sea-goddess worship of Dr. No's undressed-for-success Ursula Andress.

--The daily afternoon strolls of 14-year-old Heloisa Mendes past a bar in Rio de Janeiro caught the eye of bossa nova composer Antonio Carlos Jobim and poet Vinicius de Moraes. The Girl from Ipanema of 1964 was their ode to the local beauty.

--The 1964 film epic One Million Years B.C. presented an anti-historic view of the bikini's origins, but it starred Raquel Welch and not a Neanderthal quibbled.

--Hollywood went panting after the youth market with empty-headed endless-summer films, reaching high tide in 1965 with How to Stuff a Wild Bikini.

--Itsy-bitsy was fully realized as California bathing-beauty-next-door Cheryl Tiegs epitomized the 1970s ideal.

--And royal legitimacy was conveyed by Princess Diana in the Caribbean surf.

Now the onetime national treasure of France is a staple around the world. Lissome Brazilian teens who line the Rio beaches and boardwalks buy five or six bikinis a year and own an average of 15. On runways during Australian Fashion Week in May, the 50- year-old bikini looked hip in '70s retro suits by the designer duo of Morrissey Edmiston. An elegant lace print by Sydney's Nicole Zimmermann was snatched up for Lane Crawford, a boutique chain in Singapore and Hong Kong, and for Harvey Nichols of London- -Princess Di's favorite store.

With the passage of time, there's even a certain nostalgic appeal. Recalls Zimmermann, 28: "I grew up in a beach suburb, and that's what you wore. Everyone had a bikini." If time has passed for the wearers too, well Samantha Godsall, 29, a ri sing star among London swimwear designers, says new materials are helping. "Modern fabrics like Lycra have made the bikini more wearable," she observes. "Today's bikini offers more support, and the body-conscious woman is able to don a biki ni in confidence.'' Heloisa Mendes Pinheiro, the muse of the Ipanema anthem, is 48 and the mother of four. She has seen and worn nearly all the changing bikini fashions for the past 30 years, but now says, "Today I hide a little more."

If once the question was whether it could stay on, today the bikini is obviously here to stay. When the skin-cancer scare of the mid-1980s had some women running for cover from the sun's burning rays, the one-piece bathing suit made a temporary comebac k. But even though many women on European beaches nowadays dispense with their bikini tops, the two-piece version is not about to disappear. "Fashion is always the next step toward where we are headed," notes critic Hollander. The bikini pointed to an era of opening up and still seems to. Invented at a time when optimism was in the air and hedonistic pleasures were beginning to be celebrated, the breezy little bikini shows no sign of growing up or growing old.

--Reported by Bruce Crumley/Paris, Michael Fitzgerald/Sydney and Ian McCluskey/Rio de Janeiro