Fact No. 1: France is famous for enjoying the best quality of life on the Continent. Fact No. 2: The French seem to think that their country's best place to live is not a tourist magnet like Paris, Nice or Toulouse, but lesser-known Nantes, a city of 550,000 close to the Atlantic coast. In 2003, the weekly L'Express voted Nantes the Greenest City, and the weekly Le Point named it Best Place to Live in both 2003 and 2004. Put it all together and the conclusion becomes inescapable: Nantes must be the most livable city in all of Europe.

Socialist Mayor Jean-Marc Ayrault, 54, whose environment- and family-friendly policies have led to much of the acclaim, says his ambition is to make his town "a city that counts in Europe." Wherever you go in Nantes, you can see what Ayrault and his city planners have achieved over the course of his 15-year tenure. Recycling and conservation programs have resulted in 1,000 hectares of greenery and 95 parks and squares around the Nantes area; 70% of all waste is recycled. There are 500 km of bicycling and walking paths, which often hug the banks of the Erdre River. Even the city center feels light and airy, with wide sidewalks and streets, and a skateboarding park near the heart of town. But Nantes' pride and joy is its transportation system, which includes a tramway network and a fleet of 155 buses that run on natural gas. It's not hard to see why Emilie and Sebastien Loizeau picked this place when they moved back to France in 2003 after five years in Dublin. The couple recently opened a brasserie on a quiet street a few steps away from the city center, and are doing brisk business. "We wanted an affordable city that wasn't too big, but had lots of culture, yet a countryside spirit as well," says Emilie, 27, as she serves coffee to one of the regulars. "I like the relaxed pace of this city ... Plus, you can go everywhere on the tram."

The Loizeaus are part of a larger migration into Nantes. Between 1990 and 1999, the city saw a 10.3% jump in population — the largest increase in any French city during that period — to become the sixth largest in the country. Some of these new residents have been Parisians fleeing the expensive capital (just two hours away by TGV train) in search of good jobs, affordable housing and a safe environment. "I think that generally speaking, there's a demand today for a certain quality of life," says Ayrault, a tall, gray-haired man with a formal demeanor. "With more people choosing to live in cities, there's a need for an environment that is pleasant, that balances economic activity, work, well-organized public services and daily life." He's made it his business to achieve that balance in Nantes. In addition to the physical transformation of the city, the mayor has earned widespread praise for innovative social programs, such as guaranteed day care for all parents who need it, at a cost scaled to their income.

So far, at least, the population boom has not affected Nantes' cozy small-town feel, but it is having some impact on real-estate prices. Realtor Antoine Tuset says prices have been rising 10-15% a year. "When I began working here in 1996, we had a lot of properties and our worry was finding buyers," he says. "Now, it's the opposite, trying to find good locations to meet the heavy demand." Tuset says many of his clients are "empty nesters who've already raised their children in homes on the edge of Nantes, and now are moving to the city center, into modest apartments where everything is all right downstairs." But he mostly gets young couples moving to Nantes for jobs and a more relaxed lifestyle than they find in Paris.

Jobs aren't hard to come by. Since the early 1990s, Nantes and its neighboring port of St. Nazaire — the two have an economic-political partnership called the Métropole Atlantique — have attracted major industry to the area; companies like IBM, Airbus, Cap Gemini, Oracle and La Poste have all set up regional offices. The area is also becoming a high-tech hub, with dozens of biotech firms basing their headquarters here. The result: out of France's 100 departments, Loire-Atlantique, which encompasses Nantes and St. Nazaire, has added 100,000 jobs over the past decade, the most outside the Île de France region, which includes Paris.

For Ayrault, the influx of investors and settlers is a vindication. He's now pursuing more ambitious projects to bring not just new housing and business, but also community sports facilities and still more green spaces to relatively underdeveloped areas of the city. For this mayor, who is also a deputy and the Socialist Party leader in the National Assembly, the ideal city is one where "the people feel they have a stake in it, where the city is in their skin, where they choose to be a part of a community. This makes it easier to legislate and easier to surmount problems."

The mayor's obvious pride has rubbed off on his fellow citizens, even those who feel compelled to mar the city's beauty. In the alley next to a nice café near the Place du Commerce, scrawled in white spray paint across a brick wall is the distinctly unhip slogan: STAY CLEAN AND POLITE. Finally, graffiti even city planners can agree with.