Windy City's Park d'Arte

Its official name may be "Cloud Gate," but, in typical Chicago style, locals here have already given it their own title: "the bean."

Friday night, the giant, silver, decidedly bean-shaped sculpture is just one of several much-awaited attractions Chicagoans will see up close for the first time, as Millennium Park - one of the most ambitious city park projects in decades - opens its gates with pomp and fanfare.

It's been a long time coming. Some here were starting to joke about just which millennium the 24.5-acre park, originally set to open in 2000, was meant for. And for months, visitors have peeked through fences as the park took shape, offering assessments on the architectural value of structures like Frank Gehry's singular bandshell, easily visible from Michigan Avenue.

Since Mayor Richard Daley announced his plan in 1998, the park has expanded considerably, tripling in budget and evolving in scope from a simple extension of Grant Park that would cover some unsightly railroad tracks to a landscape with lofty cultural and architectural aspirations - a space that many hope will become a major tourist destination.

The 18-block park has been funded, to an unprecedented degree, by private and corporate sponsors, who've footed almost half of the $475 million tab. And it's emerged as a model for other cities, from Irvine, Calif., to St. Louis, looking to subsidize the cost of city parks by way of private and corporate donations.

In Chicago, Millennium Park is the culmination - and the most ambitious - of a long list of improvements undertaken by Mayor Daley, a leader with a penchant for greenery and city makeovers. And its association with the mayor may also explain why the park has encountered so much controversy along the way, for everything from its ballooning budget to its architectural eclecticism to the advisability of putting so much emphasis on one downtown area.

But this week, the news coverage is celebratory. Chicagoans are notoriously proud of their city, and they're eager to embrace anything that adds to its cachet.

"I think this is putting us back on the architectural map," says Edward Uhlir, the chief planner, as he walks through a hive of workers scrambling for opening day. "Picasso for a while was the icon for Chicago. Now we have three more."

The icons he's referring to are three of the park's more high-profile elements: Anish Kapoor's "Cloud Gate," a stainless-steel bean that reflects the park, the skyline, the clouds, and visitors themselves; the curving silver ribbons of the Gehry building - formally known as the Jay Pritzker Pavilion - and the graceful latticework of pipes that covers the lawn around it; and Crown Fountain, framed by two massive towers with ever-changing videos of 1,000 Chicago faces, their mouths periodically shooting water into the reflecting pool below.

If that sounds like a lot for 24 acres, consider that there's also an ice-skating rink, a Gehry-designed bridge, a major new theater, a promenade, a bike storage and rental facility, and a three-acre garden designed by landscape architects Kathryn Gustafson and Piet Oudolf.

Verdant glens and open lawns this is not, and some have criticized the dearth of park-like space. But there's no denying the park's ambition, or even its archetypal Chicago-ness, squeezing in as much of the biggest and best as it possibly can. It's a fitting extension of architect Daniel Burnham's 1909 vision for the lakefront. He famously advised: "Make no little plans - they have no magic to stir men's blood."

These big plans helped draw donors, whose push for a more ambitious park was part of the reason for the delay. When Daley first called John Bryan, a prominent Chicagoan and former head of Sara Lee, to ask if he could help raise private donations - an unusual move in itself - Mr. Bryan realized there was potential to go far beyond the initial plans. (The mayor had suggested tapping the private sector for $30 million, a small fraction of what it ultimately raised.) He couldn't be more pleased with the result.

"We see this as a major definition of Chicago to the world," Bryan says. "And it will be run as free as it possibly can. It's kind of a gift to the people of Chicago from the city."

But not all Chicagoans are so happy. Many see it as another splashy ornament taking money and attention away from schools, neighborhoods, and other urban issues. "It's just another example of Daley getting his way," says Patricia Nolan, director of planning and research for the Neighborhood Capital Budget Group, a civic watchdog group. "He's very into these high-profile, grandiose, monumental projects, with no thought of what the public wants or needs."

Most of the public financing comes from revenue bonds generated by a new parking garage beneath the park - money that couldn't have been spent elsewhere. But Ms. Nolan is upset about the $95 million the city took from a downtown tax fund to redevelop the loop. Since there was a surplus, she says, it would have gone back into the 2007 general budget.

Others have criticized the park itself, saying it lacks a cohesive design. "Millennium Park is kind of a collection of one-liners," says Brent Ryan, co-director of the City Design Center. "As individual works of art, they all achieve their particular goals.... But did Millennium Park succeed in making Grant Park a more humane place? I'm not quite so sure." Professor Ryan says he was disappointed to see the park cater to drivers - partly a result of financing from the garage - and he'd have liked a little more "passive" recreational space.

As the city celebrates the opening, though, with a no-holds-barred festival that features symphony programs, dance troupes, clowns, tours, and improvisational jazz, most eyes will be focused on what has been achieved here. It's hard not to be a little in awe, seeing a great city reflected in the shiny surface of "Cloud Gate," or looking up at the skyline through Gehry's gravity-defying ribbons.

The initial, less ambitious plan, says Mr. Uhlir, was more in keeping with Grant Park's old Beaux-Arts style. But he and others envisioned something more. "I didn't want a slavish repetition of the Beaux-Arts planning," he says. "We decided to do something much more radical and fun. After all, it's Millennium Park. We didn't want to be celebrating an era of two millenniums ago."