CHICAGO – They came from Holland and Mexico, from Scotland and Italy. On a cold January day, tourists descended on Chicago’s Millennium Park just as they do when it’s warm and the crowded ice skating rink turns into a crowded restaurant.

As the city prepares to make public a detailed explanation of its bid for the 2016 Olympic Games on Tuesday, organizers say such scenes help illustrate that Chicago is a global city with the cachet to host the most global sporting event of all.

But those same tourists reveal something else: the stubborn perception that, long since the stockyards, steel mills and gangsters like Al Capone disappeared, Chicago remains a gritty city of belching smokestacks and dangerous streets.

“I thought it would be more industrial than it is,” said Carol Morrison, of Edinburgh, Scotland.

“They think it’s a very criminal city,” Teresa Speller, said of her countrymen in Holland.

Those supporting Chicago’s Olympic bid know that changing the city’s image among outsiders is crucial if they are to convince the International Olympic Committee to pick Chicago.

“The great assets of Chicago have to be made known to the world,” said Patrick Ryan, leader of the city’s 2016 organizing committee.

He said most international travelers do not venture past the east or west coasts, so they’re far more familiar with cities like New York, Los Angeles and San Francisco. Foreign visitors to Chicago say their friends back home simply don’t think of the Lake Michigan city as a vacation destination.

What they know about Chicago often comes from movies and television shows,often painting the city as a somewhat ominous if not downright violent place.

Lost in all this, say Ryan and others, is the natural beauty of a city on the shores of one of the nation’s largest lakes, the gleaming skyscrapers, beautiful parks, museums and other cultural attractions.

In 2005, Time magazine named Mayor Richard Daley one of the nation’s top five big-city mayors. That year, a Boston Globe correspondent called Millennium Park “the best urban public park I’ve ever seen, anywhere, and that includes some famed ones in places like Rotterdam and Paris.”

The next year, The Economist published a flattering story about Chicago’s “revival,” calling it “a city buzzing with life, humming with prosperity, sparking with new buildings, new sculptures, new parks and generally exuding vitality.”