PARIS >> For reasons that may never be known, maybe just by chance, the Nov. 13 assaults here, which killed 130 people, skipped over the shops, outdoor cafes and theaters along Rue Jean-Pierre Timbaud. The Bataclan theater is just around the corner; the Café Bonne Bière, where five died, is a short walk the other way.

Rue Jean-Pierre Timbaud was not only the eye of the storm but also the essence of what the terrorists were targeting, which was more than a theater, a stadium and terraced cafes. They were targeting civic pluralism and street life: a kind of urban compact they loathed and feared, but whose fissures, however subterranean, they could exploit.

With its bobo bars toward one end and Muslim enclave at the other, Rue Jean-Pierre Timbaud is Paris in a nutshell. People live together on the street, but separately. Vee Gomes, a Dutch-born hairstylist, tells a story about setting up her business on Rue Jean-Pierre Timbaud a couple of years ago.

“I opened my shop between two other hairdressers,” she recalled one recent afternoon, sitting at an inlaid wood table, piled with books, near the front of Vee Hair. “I thought they would be furious.”

But, Gomes said, “that’s not how it turned out.”

The shops, though steps from one another, turned out to occupy separate worlds and serve separate clients whose paths hardly crossed.

“We have different clients, different prices, different styles,” she said.

So it is with life on the street at large, which Jean-Louis Cohen, a French architectural historian, described as “a lively place where Parisians and many people have lived forever.” Cohen remembers, as a young man, prowling the Marxist book sales at the former metalworkers union headquarters on the street. Now, gentrification is the big threat.

“It’s still a mixed street, not too touristic, like the Marais, which is becoming sterile,” he said. “There is a notion that all French social housing is in the suburbs, but this is an area that has social housing alongside bourgeois housing.”

That said, a mosaic is not a melting pot. Coexistence and integration are not the same. After all, while the old Jacobin ideal of French republicanism imagines a colorblind nation based on liberty and equality, on the ground, the country remains a patchwork of racial divisions and other boundaries, visible and not. Headlines lately have fixated on borders: the ones colonial powers drew in the Middle East after World War I; the ones the Islamic State militant group has redrawn in Syria and Iraq; the ones Europeans now debate closing.

But most borders in cities are invisible. They are porous, shifting, forever being negotiated and renegotiated, block by block.

To walk along Rue Jean-Pierre Timbaud today is to find a mix of peoples and borders. A big blue, white and red banner hangs across the Omar mosque. “Not in My Name,” it says. Soldiers stand outside Jewish schools around the corner on Rue Saint-Maur, stamping their feet against the cold. Like much of Paris, this part of the city maintains a proud and uneasy equilibrium that now passes for normal.

A storekeeper at a bookshop, Al-Azhar — which, like the half-dozen or so other bookshops and Islamic clothing stores clustered around the mosque, sells prayer mats, incense and candy — said, “Since the attack, people in the neighborhood look differently at us.” He declined to give his name.

On Friday afternoons, hundreds of men — the overflow crowd from the mosque — pray outdoors, in the middle of Rue Jean-Pierre Timbaud, on the little square facing the stores, with a few congregants keeping a wary eye on passers-by.

“We don’t want trouble,” the storekeeper at Al-Azhar said.

The mosque preaches an ultraconservative version of Islam, and associates of Amedy Coulibaly, the man who killed four hostages at a Jewish supermarket in Paris early this year, were reported to have frequented it. Lately, the imam has reached out to a synagogue in the neighborhood and to the Catholic school next door.

“It’s not his responsibility to police everybody who goes there to pray,” said Bernard Godard, a political scientist in France’s Interior Ministry, who specializes in Paris’s Arab communities and has been studying Rue Jean-Pierre Timbaud since the 1970s. “Islam in France is generally conservative and tells Muslims to respect the Quran, even to be opposed to certain ways of life in France. But that doesn’t mean to be violent.

“The typical French person thinks that this mosque is radical because it is fundamentalist,” Godard added. “The Muslims on Rue Jean-Pierre Timbaud exist side by side with the bobos and everybody else. The street is neutral ground.”

Up to a point, anyway. Philippe Mourrat directs the Maison des Métallos, a city-run culture center directly across the street from the mosque, in what used to be the metalworkers union headquarters where Cohen went book shopping. The center hosts lectures on climate change and evenings of calypso dancing. Five years ago, two men poured gasoline over an Algerian playwright, Rayhana, who had been hired by the Métallos to present a play about women in the Maghreb. Bertrand Delanoe, then Paris’ mayor, and Frédéric Mitterrand, then France’s culture minister, expressed outrage. The attackers, who failed to set Rayhana on fire, were never caught.

Mourrat characterized that event as an exception in the neighborhood. During a recent Ramadan, he pointed out, men praying at the Omar mosque rushed to defend a patron who was mugged as he left the Métallos.

But Godard said he saw that episode differently, as an example of growing tensions over gentrification. For many years, the area was home to small-time craftsmen and industrial warehouses. It was a working-class hub and immigrant magnet. Jews from the Alsace region moved to Rue Jean-Pierre Timbaud before World War I. Marc Bédarida, an architect who settled on Rue Jean-Pierre Timbaud in the early 1980s, remembers that the storefront on the ground floor of his handsome 1840s apartment building, which now houses a fancy hairdresser, used to be a wholesaler of doorknobs. The chain-store grocery across the street used to be a warehouse for industrial shelving.

Factory jobs attracted waves of postwar immigrants from Algeria, Morocco, Tunisia; some Chinese, too. Jean-Pierre Timbaud was a labor leader murdered by the Nazis. He headed the metalworkers union in a former piano factory.

There are many beautiful industrial buildings up and down the street. They fell vacant when the economy collapsed and jobs dried up, leaving behind 1970s social housing and prime real estate for the creative classes. Architect Jean Nouvel opened his office just off the street in 1994 in a former workshop for making bags; his longtime assistant, Charlotte Kruk, recalled the other day that it had been a ramshackle site with dead pigeons on the floor.

Now, the area is a little reminiscent of Saint-Germain-des-Prés in the 1970s.

“It’s a district of advertisers, designers, graphic artists,” Nouvel said. “You have bars and cafes, but not yet for the very rich. So it’s a hybrid situation, a kind of meeting place for lots of different types of Parisians — although with apartments becoming very expensive, you see changes. The Muslim population is decreasing.”

The other morning, I stopped in to Kol Yehouda, a bookstore on Rue Saint-Maur, just around the corner from the Omar mosque. The young salesman would give only his surname, Cohen. He said Jewish residents in the neighborhood used the market that opens at one end of Rue Jean-Pierre Timbaud on Saturdays and Sundays.

“We see each other; we don’t talk,” he said. “It’s calm and normal.”

Rue Saint-Maur roughly marks the present tide of gentrification where it crosses Rue Jean-Pierre Timbaud. Bobo bars, so called because of their “bourgeois bohemian” clientele, have crept up to Saint-Maur, but only a few share the Muslim area: among them the Café Cannibale, where you can order Norwegian brunch and Japanese whiskey, and where old men from the neighborhood read the newspaper Libération over coffee at the zinc bar.

Farther down the block, market stalls sell fruits and espadrilles under ranks of colored umbrellas and corrugated metal roofs along Boulevard Richard-Lenoir, another invisible border of sorts. At the far end of Rue Jean-Pierre Timbaud, bankers and hedge fund guys are moving into apartments.

“The Paris that most Americans know is not this place,” Gomes, the hairdresser, said. “They know the Marais and the Champs Élysées and” — she wrinkled her brow, as if trying to retrieve some obscure name — “Saint-Germain-des-Prés.”

“Here,” she said, “you find locals, architects, actors, people with cash.”

Muslims and Jews, too, I said, who have been around longer.

“I have Jewish and Muslim clients,” Gomes replied. “We live on the same street. But we don’t mix. That’s Paris, no?”

She waved through the storefront window. “We are all together, on our own, and wave to each other.”

© 2015 The New York Times Company