Ever since Fred Astaire and Ginger Rogers appeared in the 1933 film Flying Down to Rio, the world has been fascinated with Rio de Janeiro. Popular perception of the city is infused with images of starry-eyed youngsters dancing into the dusk, backed by imposing mountains and dark sea.

That view has propelled Rio to the top of our list of the world's happiest cities. Famous for its annual Carnaval festival (starting Feb. 13 next year), the second-largest metropolis in South America finished first among 50 cities in a recent survey conducted by policy advisor Simon Anholt and market researcher GfK Custom Research North America.

"Brazil is associated with all these qualities of good humor and good living and Carnaval," says Anholt. "Carnaval is very important--it's the classic image that people have of Rio, and it's an image of happiness."

Next on the list is the top city from Down Under: Sydney, Australia. Known for balmy weather, friendly locals and an iconic opera house, Sydney fared well in Anholt's survey because of its association with a popular brand--Australia.

"It's where everybody would like to go," he says. "Everybody thinks they know Australia because they've seen Crocodile Dundee. There's this image of this nation of people who basically sit around having barbecues."

Rounding out the top five are third-ranked Barcelona, Spain, which Anholt calls "the classic Mediterranean city"; fourth-ranked Amsterdam, Netherlands, because Anholt's young respondents "know you can smoke dope in the bars"; and Melbourne, Australia, which makes the list simply because it's in Australia.

"People know it's in Australia, and that it's full of Australians," says Anholt. "Therefore, it must be fun."

Behind the Numbers
The data Anholt provided for our list is part of the 2009 Anholt-GfK Roper City Brands Index, released in June. The research was compiled through online interviews with 10,000 respondents in 20 countries.

Happiness is difficult to quantify, and Anholt acknowledges that his data is less an indicator of where local populations are happiest than a reflection of respondents' thinking about where they could imagine themselves happy.

"This is a survey of perception, not a survey of reality," he says. "People write me all the time and say 'that's not true.' It probably isn't true, but it's what people think. The gap between perception and reality is what interests city governments."

The French historian Fernand Braudel wrote that "Happiness, whether in business or private life, leaves very little trace in history." (More quotes on happiness.) But a perception of happiness leaves a strong trace on the balance sheets of cities that depend on conventions, tourism and an influx of talent.

The Pursuit of Happiness
Anholt notes that the results of his survey reflect the longstanding reputation of Mediterranean and Latin American cities as non-stop party locales.

"It's pretty much the expected bunch," says Anholt. "Though I'm a little surprised about Spain outdoing Italy. It's interesting that the Spanish are perceived as being happier than the Italians--I find the Spanish rather gloomy."

Still, Barcelona--Spain's highest-ranked city--has plenty of supporters.

"The beauty of the city and its environs, along with affordable housing and business opportunities, is the fantastic lifestyle," says Michelle Finkelstein, a vice president at travel agency Our Personal Guest. "There's not the stress of getting a child into the best preschool--the public ones are good and close by. And they have the top soccer team and some of the best weather in Europe."

Other places in the world that lack the metropolitan flair of the cities on this list are often identified with the notion of happiness. "Anyone lucky enough to visit the magical Himalayan kingdom of Bhutan would know that there is no competition: There can be no happier place," says Patricia Schultz, author of 1,000 Places to See Before You Die. "This small Buddhist nation of incredibly stunning beauty follows a unique guiding philosophy of GNH--Gross National Happiness. You can see it in their open faces--they smile from the heart. Barcelona has nothing on them."

Global rivalries notwithstanding, Anholt notes that his findings more or less support historical trends, with one notable exception.

"The cities on this list would probably be the same if I'd been running this survey in 1890, aside from Sydney and Melbourne," he says. "Australia is kind of a branding miracle."

Not bad for a former penal colony.