SHANGHAI, Sept. 28 — Somehow all conversations at the Paramount ballroom in Shanghai manage to wend their way toward what might ordinarily be considered an unwelcome topic: the ballroom dancers’ ages.

The Paramount is just that kind of place, a palace of retro in a city with its gaze fixed far more intently on a bright-looking future than on its often brilliant but tumultuous past.

But more often than not, it is the dancers who bring up the question, proudly daring a visitor to try to guess their age.

It might be a rich business tycoon in his 90s who shuffles through halting steps propped up by a fine-boned dance partner seven decades his junior. Or it might be a well-heeled tai-tai, a Shanghai homemaker out for her regular escape from tedium.

The reason the age question comes up with such regularity is not because this relic of a place makes its habitués feel old — quite the contrary. Whatever their description, the regulars here are all but unanimous on one point: it’s their frequent turns at the fox trot or the tango or the rumba that help keep them feeling young.

“Look at me, I’m still upright,” said a slim and stylishly dressed woman who gave her name only as Yoshimi. “I don’t go the gym and I don’t diet, either. My regimen consists of coming here twice a week and enjoying myself dancing.”

With a wink, the woman, a 49-year-old Paramount regular, who is half-Chinese, half-Japanese and divorced, added: “And it works.”

In a city that is rapidly losing the remaining traces of its last great boomtown era in the first decades of the 20th century, the Paramount has not only somehow managed to survive. It stands out.

By early evening, its approaches are clogged with hurrying commuters talking quickly into cellphones and dodging sidewalk vendors hawking everything from copied DVDs to Shanghai-themed Monopoly boards on narrow, hectic side streets.

Turn onto Yuyuan Road, though, and no matter how many times one has seen it, there is a moment of surprise. With its bright neon Art Deco trimmings, the building could be a giant and lavish set prop from the Buck Rogers era, or a gaudy transplant from the old Miami Beach.

That the building has survived to stand in this form today, though, has been a small miracle, considering the countless reincarnations it has undergone since it was built in 1933 by Chinese bankers. It started out as a casino and favorite gathering place of high society, but went steadily down the economic ladder, first as a favorite after-work stop for government clerks and other members of a growing Chinese middle class, and then deteriorating into a preferred hangout of wiseguys and their molls.

“The dancing culture was so popular that almost everyone in the office, what we call white collar workers today, or bourgeoisie, people who work for foreign companies, would go dancing after work,” said Chen Zishan, a professor of language and literature at East China Normal University, in Shanghai.

The Paramount was not the city’s only ballroom. At the peak of the dancing craze, in the late 1930s, there were at least 200 of them. But the Paramount, with its auspicious-sounding Chinese name, Bai Le Men, or Gate of 100 Pleasures, was situated right where the city’s so-called International Settlement and its indigenous quarters converged, and thereby came to occupy a special place in the city: a meeting point of the two worlds.

Very often, this came to mean well-heeled Western men and Shanghai’s famed taxi girls, who vied to sell their services as dancing partners and escorts.

“When guests wanted to flatter a popular dancer or to promote them, they would ask the girl to sit beside them and give them gold ingots,” said Qiu Suhui, a manager of the ballroom. “Most of the guests were rich or powerful people, and the dancing girls were the most sociable and beautiful women in Shanghai. The dancing room was old Shanghai in miniature.”

When the Communist Party took power in 1949, the city’s moneyed classes fled or faced persecution, the taxi girls disappeared, jazz was banned and finally, in 1956, the Paramount was closed. Sometime later it reopened under a new name, the Red Capitol Cinema, and became a place for uplifting Socialist films and productions.

As the decades passed, the once-grand building grew ratty. In the mid-1990s, as China’s economic reforms came belatedly to Shanghai, a portion of the building was turned into a small movie theater. It was not until 2001, when a Taiwanese businessman, Zhao Shichong, invested $3 million for its renovation, that the building began to recover some of its original grandeur.

Today, the walls of a red-carpeted stairway are lined with glamour shots of Shanghai starlets from 70 years ago. Big-band music oozes out into the corridors, and when visitors finally step into the ballroom, the highly polished wood floors, the dramatic lighting and the couples that seem to float about have been known to give people a flashback.

It can feel like being aboard a great ship in the heyday of ocean liners. What’s certain is that 2007 seems far away.

For Wu Yongmei, a successful, semiretired businesswoman who owns a large air-conditioning company, that’s just fine. “I once went to the Paramount just to have fun and saw the people dancing and felt so jealous,” she said. “It was so beautiful.”

Ms. Wu, like many of today’s well-heeled regulars, visits frequently, usually in the afternoon, when the serious dancers turn out. Like the others, she takes private lessons and chooses her outfits carefully.

“If someday the Paramount closes, even if they say there is some other place to dance, it won’t mean anything to me,” said Ms. Wu, who is in her early 50s. “This is old Shanghai, and as a Shanghai person, if there’s no more Paramount, it just won’t suit me.”