People walking the streets of Pittsburgh, the host city of the G20 economic summit, can see welcoming signs almost everywhere.

With leaders of the world's 20 largest economies and thousands of visitors coming, this Pennsylvania city is trying to show off its new image as a role model for recession-battered communities because of its transition from a smoky industrial city to a haven for diversified, green businesses and higher education.

Rows of discarded, shuttered buildings dotting both sides of the Allegheny River are reminders of Pittsburgh's steel-town past while buildings sporting the logos of hi-tech and green-energy companies advertise the city's rebirth.

Pittsburgh is an icon of economic transformation. That's why it was chosen by US President Barack Obama as the venue for the two-day summit.

"Pittsburgh stands as a bold example of how to create jobs and industries while transitioning to a 21st-century economy," Obama said earlier this month. Pittsburgh, he said, "represents the transition of the US economy from an industrial state to a mix of strong industries."

The city "will provide both a beautiful backdrop and a powerful example for our work ... in a place known as the city of bridges, we can come together to advance our common interest in a global recovery," the president said.

Pittsburgh is famous for its links to the long-gone steel industry. The decline of steel in the early 1980s left Pittsburgh with staggering unemployment and thick air pollution that sometimes made the city barely visible, Christ in Mitchell of the city's tourism authority told Xinhua.

Mitchell said, however, that three so-called renaissances that Pittsburgh underwent after World War II changed the city inside and out.

The first renaissance began in 1945, when then-Mayor David Lawrence implemented an urban renewal plan to reverse Pittsburgh's image as a "smoggy city."

The second came in 1976 when then-Mayor Richard Caliguiri initiated the construction of such skyscrapers as the PPG Place.

The year 1994 saw the city begin its third renaissance, which led to the construction of a number of so-called green buildings, including the David L. Lawrence Convention Center, where the summit will be held.

Through the renaissances, Pittsburgh completed its transformation from a gray, blue-collar city to one that now features a number of diversified industries, including technology, research and health care.

Apart from the so-called green businesses, the city also hosts two of the nation's biggest financial institutions, Mellon Financial and PNC Bank. Heinz, Alcoa, US Steel, and PNC Financial are among the other major companies based in Pittsburgh.

In addition, the city has made a determined long-term transformation from its blue-collar roots to white-collar jobs, with strengths in financial services and higher education. Two famous universities -- Carnegie-Mellon and Pittsburgh -- are both located in the city.

A good environment, rich culture, quality education and low cost of living led the British magazine The Economist this year to rate Pittsburg as one of the most livable cities in the world. It was the only US city on the list, Mitchell said.

With such a successful turnaround, Pittsburgh also is the perfect place for the Obama administration to show the US and the world just how parts of its giant stimulus plan will work in the future, some analysts say.

Pittsburgh is receiving its fair share of federal dollars to revamp its airport and invest in the area's burgeoning green energy workforce.

Pittsburgh offers a glimpse of how a city can emerge from a declining past to a seemingly promising future. In return, it is set to collect a global public relations bonus from the 3,000-plusjournalists and other visitors expected in the city during the summit.

"The summit will definitely give a boost to our city's tourism," Mitchell said.

Visit Pittsburgh estimates that the summit will deliver a minimum boost of 20 million to 30 million US dollars to the local economy, with a potential long-term benefit of 100 million dollars.