Just a short drive from the opulence of Versailles Palace, a closed-off community of strictly conservative Muslims is posing the most visible challenge to French authorities hoping to stem the rise of homegrown extremists.
At first glance the town of Trappes, where urban renovation projects have replaced dozens of grim tower blocks, doesn't match the stereotype of poverty-stricken enclaves offering fertile ground to jihadist recruiters.
While never quite shaking off its rough reputation for drugs and violence, the town southwest of Paris has produced international football star Nicolas Anelka and popular French-Moroccan comedian Jamel Debbouze.
These days every butcher shop in the town-centre is halal and most women at the market wear headscarves, and increasing numbers of local Muslims adhere to Salafism, a Sunni branch which promotes a strictly conservative lifestyle.
While most French Salafists disdain violence in following the traditions of "pious ancestors", many of the jihadists who have struck France in the past three years have been associated with the movement.
And a security source told AFP that around 50 people from Trappes -- which has a population of 30,000 -- have gone to fight in Iraq or Syria.
"It's a tragedy," said Ibrahim Ayres, owner of an Islamic bookstore who says he himself managed to dissuade five young people from joining the Islamic State group.
Authorities and locals also see the Salafist influence as behind the sharp drop in the town's crime levels.
"In the 1970s and 80s, the delinquency rates were much higher. Mothers were relieved when they saw their children start practising their religion again," said Ayres, who has a white beard and a long traditional robe.
"Muslims didn't see what was behind it."
- Clash with French secularism -
The radicalisation of what has been called the "French Molenbeek" -- a reference to the Brussels district which was home to several of the jihadists involved in the 2015 Paris attacks -- has mirrored the rise of Salafism across France.
While still a minority among the country's estimated six million Muslims, security forces say their numbers have soared from 5,000 in 2004 to between 30,000 and 50,000 today.
Back in the 1990s, Trappes had been a source of militants for the Armed Islamic Group of Algeria (GIA), which staged a series of attacks in France throughout the decade.
The town developed quickly in the 1960s with the arrival of North African migrants seeking work in nearby auto factories, but today unemployment is around 20 percent -- double the national average.
Tensions burst into the open in 2013 after a man was arrested for allegedly attacking a police officer who stopped his wife for wearing a full-face veil in public.
"There is a clear intention to mark religious adherence in social life," says Trappes' Socialist Mayor Guy Malandain.
A group of 200 women recently came to his office asking for women-only hours at a local swimming pool, which he refused in the name of France's strict secular principles.
He also stopped calls to prayer blaring from a loudspeaker at one of the town's five mosques, run by a group thought to be linked to the Muslim Brotherhood -- which refused to speak to AFP.
In 2016, a confidential report by justice officials found nearly 80 families in Trappes were home-schooling their children instead of putting them in local schools.
All of which has caused unease in a country where politicians tend to emphasise shared values and often express concern over communities "shutting themselves off" from mainstream French society.
- 'Wind in its sails' -
Allal, who runs a cafe near the market, says he doesn't know any Muslim fundamentalists. "They don't come here, they don't speak to me," he says.
Yet since he stopped serving alcohol in 2015, his business "has quadrupled" and during a recent sweep by police "they didn't find a gram" of drugs, he says.
But such claims do little to ease fears in France which has been on high alert since early 2015 when the wave of jihadist attacks began that have so far killed more than 240 people.
"What worries me are the growing calls for an isolated cultural identity," said Othman Nasrou, a local lawmaker.
Some officials want an outright ban on Salafism, a move dismissed as unrealistic by legal experts but which echoes a widespread view that recent laws aimed at curbing extremism haven't done enough.
"How can you outlaw an idea?" said Rachid Benzine, an Islamic expert who was born in Trappes.
Yet he acknowledged that Salafism "encourages a split with one's environment which can at times open the door towards jihad".
"It has the wind in its sails, and will continue to develop so long as there is nothing to counter it," he said.
France doesn't produce official statistics on religion but Trappes' mayor estimates 25 to 30 percent of its residents are Muslim -- though a local legal source suggested the number was more than double, at between 60 and 70 percent.
Malandain hopes President Emmanuel Macron will clarify the state's response in a coming plan for bolstering ties with France's Muslims.
"If we don't emphasise the role of advocates of a moderate Islam, a European version, we're going to have serious problems," he said.