The famous skyline is etched with distinctive buildings. The downtown boasts a vibrant cultural district. And the stunning lakefront and art-filled parks attract thousands of visitors every day.
The Chicago of 2012 is a sparkling, fast-globalizing financial-services center and a cradle for high-tech startups. Yet in much of the world, the nation's third-largest city is more likely to conjure images of long-dead mobsters, demolished steel mills or a red-faced Mayor Richard J. Daley defending how police cracked protesters' heads at the 1968 Democratic National Convention.
So it's difficult to overstate the importance of this weekend's NATO summit to business and tourism leaders -- or how critical it is for the event to unfold smoothly, despite the potential for large protests.
"We ought to be known for something more than the old stockyards, smog or Al Capone, but we aren't," said Richard Longworth, a senior fellow at the Chicago Council on Global Affairs. "People are surprised when they visit, and that's why" Mayor Rahm Emanuel wanted the summit.
"We have to stop being a surprise," Longworth added.
Twenty-first century Chicago depends more than ever on its international reputation in the quest for jobs, investment from abroad and markets for its exports. Yet it still struggles with familiar problems, such as subpar schools, segregation and corruption. And in its last attempt to draw world attention, a bid for the 2016 Olympics, the city was embarrassed to be eliminated in the first round.
Chicago has changed profoundly since the 1968 debacle. Back then, the steel mills still belched smoke. The stockyards, while a shadow of what they had once been, were still a couple of years from closing altogether, as anyone with a nose could tell you when the wind shifted.
What had long been one of the most racially divided cities in the nation was also angry, on edge. Big chunks of it were still smoldering from the rioting that followed the assassination of Dr. Martin Luther King Jr. And nobody had forgotten the mayor's still-famous order to shoot to kill arsonists and shoot to maim looters.
In the years since, a second Mayor Daley has come and gone. Richard M. Daley, who took over the city 10 years after his father died and retired in 2011 after 22 years in office, is largely credited for leading the transformation from a gritty industrial center to a booming hub of international commerce.
Chicago is now headquarters of Boeing Co. and United Continental, corporations he lured with millions in financial incentives. Donald Trump's 98-story tower is among the newest additions to the skyline. And dozens of startup companies have taken root here, including Groupon, a web sensation that has served to anchor the tech culture.
"Ten years ago, you wouldn't have mentioned Chicago" when talking about Internet and high-tech companies, said venture capitalist Eric Lefkofsky, a co-founder of Groupon Inc. and several other Internet startups.
"Today it's mentioned all the time" in the same sentence as Silicon Valley or New York. "When people come here ... they're blown away. They have no idea we have an amazing theater district, an amazing restaurant district and great shopping. They just had no idea."
Those attractions will be on full display when delegations from about 60 countries, including 50 heads of state, attend the meeting of the North Atlantic Treaty Organization on Sunday and Monday. More than 2,000 journalists will be here, too, to cover the summit, where the alliance of the U.S. and European countries will discuss issues such as the war in Afghanistan and European missile defense.
Although the visits will be brief, the potential payoff is enormous, officials said.
"From a marketing standpoint, to have that many opinion leaders from that many nations" offers an unprecedented opportunity to promote business "and the fact that we really truly are a global city," said Rita Athas, president of World Business Chicago, a group of powerful executives working with Emanuel to promote the city and attract investment.
The summit also carries potential risks, especially if the police department, which never completely shed its reputation for brutality, has violent confrontations with the thousands of expected demonstrators.
Obama took a gamble by announcing that both the G-8 and NATO summits would be held in his hometown during a presidential election year. His later decision to move the G-8 meeting of leading industrialized nations to Camp David may have been an acknowledgment of those risks.
"If there were a major clash in Chicago (at the NATO summit) and the police ended up acting with a heavy hand ... I think it would seriously undermine Chicago's reputation as an enlightened world city," said Todd Gitlin, a sociology professor at Columbia University who has written extensively about the 1968 convention, where Chicago police violently clashed with an estimated 10,000 protesters. "There is a lot riding on it."
For all of its progress, the city's global reputation has remained largely mired in the past. Even Russian President Vladimir Putin recently took a dig at Chicago when asked about possible plans to attend the NATO summit.
"Yes, they say (Chicago is) good. Al Capone lived there," Putin said.
And the city is bedeviled by longtime demons. Corruption still makes the front page, years after lawsuits and prosecutions put an official end to the infamous Chicago political machine. It's one of the most segregated metropolitan areas in the country, and it's wrestling with a budget deficit of more than $600 million. Half of public high school students drop out before graduating.
Timuel Black, a veteran civil rights activist and history professor on the South Side, said the NATO summit might be a boon for Chicago's downtown and for businesses and residents who are already successful.
But he doubts it will do anything for the most impoverished neighborhoods that have only become poorer and more violent with the loss of jobs and the widening of the gap between rich and poor.
"They're concerned about schools, health care, jobs for themselves and their kids, and they just don't see the benefit" of a NATO summit, said Black, who is 93.
Longworth, from the Council on Global Affairs, said a successful summit could attract more development and tourists.
"It is not going to solve the city's problems in one stroke," he said. "But the city really does need this exposure."