Industrial jobs make up 11 percent of the metropolitan area’s employment. Among secondary cities in France, this is an achievement. Nantes ranks third, after Lyon and Toulouse, whose employment in the industrial sector makes up 14 percent of jobs.

For the commission, which announces the Green Capital prize several years in advance, Nantes’s sustainable public transport system was decisive. The city, the sixth largest in France, has the third-highest proportion of public transport users in the country, according to Florent Lardic, an adviser to the Nantes regional authority.

The city also has ambitious greenhouse gas reduction policies (besides the elephant, the Île de Nantes is also home to a large photovoltaic power plant), and every resident lives no more than 300 meters, or 1,000 feet, from the closest green space. The prize also celebrates the city’s policy of urban densification, which aims to concentrate development in limited areas and build up rather than out, in an effort to stop encroachment on rural lands. Currently, the Nantes metropolitan area’s population is 590,000, but the region expects that to grow by 100,000 by 2030.

There is, of course, a technological component to the city’s success. As early as 2001, the city initiated municipal services on Nantes.fr. Cultural calendars were posted online. People could sign up for free e-mail accounts, either from their home computers or from one of the 150 public terminals the city set up in municipal buildings, in cultural centers and on the streets. Such early investment in information technology led to a fierce following among residents but also means that the first generation of public portals is in the process of being replaced.

The city is currently working with the Nantes School of Design to come up with innovative ways to offer terminals to the public.

Mr. Ayrault, who has been mayor since 1989, insists that the greatest components of the city’s recent success have been the changes that made Nantes a good place to live. While he does not deny the importance of employment, he says that schools and after-school programs, urban art and culture, for example, play an important role in making the city attractive.