From the backseat of my dad’s old Dodge, I would watch flames licking the night sky from smokestacks along Pittsburgh’s Second Avenue. Here, at the Jones & Laughlin South Side Works, hot ingots were shuttled by rail from the mill to the north side of the Monongahela River, where they were rolled into steel sheets.

The skies have cleared, the oily smell of rotten eggs and creosote is gone, and so is the railroad. But the river crossing remains—reborn as the Hot Metal Bridge—which I cross by bike. It also carries car traffic from Second Avenue to the new South Side Works, a gleaming retail complex and home to the Pittsburgh Steelers training facility. Downtown, a few miles away, is the David L. Lawrence Convention Center, the world’s largest environmentally friendly certified building of its kind. Pittsburgh banking giant PNC Financial Services boasts of being a world leader in green buildings, and the Children’s Hospital of Pittsburgh of University of Pittsburgh Medical Center was among the first LEED-certified pediatric hospitals in the country when it opened in May. Google opened an engineering office in Pittsburgh in recent years. So did Apple and Intel Research.

Why in the world was the City of Bridges chosen for the G-20 summit, where world leaders from industrialized and emerging economies will gather this week? To give the world a front-row seat to a city’s remarkable remake while the paint is still wet.

Meet Trevett Hooper and Mary Murphy Kiernan, part of a younger generation that returned after growing up here or wound up in Pittsburgh, fell in love with the city, and plan to stay. Hooper is Pittsburgh’s new mill worker, turning out lemon verbena panna cotta with plum compote from his upscale East End eatery instead of sheet steel.

“What Pittsburgh has that other places don’t have is quality of life,” says Hooper, 34, who lived in Maine, Boston, and San Diego before opening Legume French Bistro two years ago. “It’s a great place for entrepreneurs.”

Just how dark was Pittsburgh’s past? Think Detroit today. The difference was the stunning swiftness and scale of Big Steel’s collapse in the early 1980s. Chris Briem, a regional economist at the University of Pittsburgh, calls it “concentrated job destruction.” Every Rust Belt town has a sad story, Briem says. “Ours was far worse.”

In the Pittsburgh area between 1980 and 1985, 100,000 manufacturing jobs evaporated. Unemployment hit 18.2 percent in January 1983 (28 percent in Beaver County, a sister steel center a few miles down the Ohio River). At its peak in the mid-1980s, Pittsburgh was hemorrhaging 50,000 mostly young, working-age people yearly in outward migration, Briem says: the “Pittsburgh diaspora.”