It would twist into the sky over Chicago's lakefront like an oversized birthday candle, surpassing Sears Tower and the planned Freedom Tower in New York as the nation's tallest building.

It might, or might not, be built. But it already is drawing fire from Donald Trump, who scaled back his plans for a record-shattering Chicago tower of comparable height after the Sept. 11 terrorist attacks.

A far less well known developer, Chicago's Christopher Carley, will unveil his proposal Wednesday for a slender, 115-story tower with a steel spire that could soar higher than 2,000 feet.

Designed by superstar Spanish-born architect and engineer Santiago Calatrava, the skyscraper would rise next to Lake Shore Drive and near the entrance to Navy Pier. Its tapering glass facade would ripple like folds of drapery.

For Carley, the chairman of Fordham Co., the planned hotel and condo tower would be taller than the combined height of his last three previous projects: two towers of roughly 50 stories and an eight-story structure.

Financing for his latest project has not yet been arranged, and will largely depend on achieving prices rarely seen in a downtown market. "Is this going to get done?" Carley said. "It'll be market-driven."

But the ambitious proposal, to be called Fordham Spire, would dramatically shift the focus of Chicago's skyline, and it likely faces community opposition and the challenge of obtaining financing in what some are calling an overheated real estate market.

In addition, some contend, it must confront the specter of terrorism.

"In this climate," said Trump, whose tower might compete with the new skyscraper for luxury condominium buyers, "I would not want to build that building. Nor would I want to live in that building.

"Any bank that would put up money to build a building like that would be insane," he said.

Carley shot back that Trump's Chicago tower is playing in the same supertall league because it will be 1,360 feet tall, just 90 feet less than Sears.

"I wonder where the insanity limit is. It must be just over 1,360 feet," he said.

The verbal jousting suggests that Fordham Spire offers a test of whether the nation's post-Sept. 11 fear of heights is easing, nearly four years after hijacked jetliners crashed into the World Trade Center. Some experts say they see less fear on the skyline.

"I remember after 9/11 a lot of people announcing the end of the skyscraper," said Ron Klemencic, chairman of the Chicago-based Council on Tall Buildings and Urban Habitat, which monitors skyscraper construction worldwide. Now, he said, "the aversion to building tall . . . has diminished."

The Tribune revealed in May that Carley was working with Calatrava--the architect of the bird-like Milwaukee Art Museum addition, the Athens Olympics sports complex and the planned transportation center at Ground Zero--to design a tower on at least one of two sites along the west side of Lake Shore Drive and the north bank of the Chicago River.

Under Carley's plan, those sites would be combined into a single 2.2-acre parcel at 346 E. North Water St. The area is now an unruly patch, filled with overgrown grass, gravel, trees and a construction trailer.

From it would sprout a tower utterly different from the boxy forms found elsewhere on the Chicago skyline: A skyscraper with gently curving, concave outer walls attached to a massive reinforced concrete core.

Each floor would rotate a little more than 2 degrees from the one below. The floors would turn 270 degrees around the core as they rise, making the building appear to twist.

A spire above would soar to roughly 2,000 feet, making Fordham Spire taller than the 1,776-foot Freedom Tower, scheduled for completion in 2010, but not as tall as a tower now being built in the United Arab Emirates.

Called the Burj Dubai and designed by Skidmore, Owings & Merrill of Chicago, that behemoth is expected to reach to about 2,300 feet--the actual height is a closely guarded secret--and become the world's tallest building when it is finished in late 2008.

Currently, the world's tallest building is the Taipei 101 in Taiwan, a 101-story structure that rises about 1,670 feet.

Calatrava denied that topping the 1,450-foot Sears Tower was his, or the developer's, objective. He contended the Fordham Spire's height reflected his search for ideal proportions.

The goal "is not the highest, or the widest, but a building that wants to be special, a step beyond," he said in an interview from his Zurich office.

Carley added: "If I had my druthers, I'd like to have Sears retain the title. If Santiago thinks it's essential, fine."

Still, because of its height, the tower can be expected to become a lightning rod for opposition in the affluent, highly organized Streeterville neighborhood.

"Some people will be excited to have a landmark in their neighborhood, and some people are going to be horrified that they're going to have such a tall building so close to them," said Jim Houston, president of the Streeterville Organization of Active Residents.

The influential neighborhood group has not yet taken a position on the project.

After protests from neighbors about blocked views and increased traffic congestion, the area's alderman, Burton Natarus (42nd), recently announced he would oppose the Fourth Presbyterian Church's plan to erect a 64-story residential tower on a portion of its historic Michigan Avenue property.

But the usually cautious Natarus said Monday that he supports the Calatrava tower.

"It's going to put Chicago on the map," he said. "I'm not concerned about height. And I'm not concerned about density, because it's a sliver."

Carley and Calatrava noted that the skyscraper's thin profile--it would have just 920,000 total square feet, compared with 4.5 million for Sears Tower--would make it a benign, not overbearing, presence along the city's lakefront.

That is far better, they maintain, than two towers of roughly 50 and 35 stories, which current zoning allows. Towers of that size would be far more bulky and cast greater shadows, the developer and architect argue.

"The tower is without any doubt tall, but it is not big. It is very slender. It is extremely slender," Calatrava said.

At City Hall, reaction to the project was guarded.

"We saw the plan and we'll consider it," said Connie Buscemi, a spokeswoman for the city's Department of Planning and Development.

Besides the political hurdles, Carley must confront history, which shows that it is easy to unveil plans for a supertall tower but far harder to get one built.

Since the 110-story Sears Tower was built in 1974, several developers have floated plans for supertall towers in Chicago, including the 125-story Miglin-Beitler Tower in 1989 and the 112-story 7 S. Dearborn project in 1999.

Yet only Trump actually has gotten such a project under way. His 92-story hotel and condo tower is now under construction along the Chicago River.

Still, Carley has less product to sell than Trump. Even though it would be taller than the Trump International Hotel & Tower Chicago, the Fordham Spire would have far fewer units--about 200 hotel rooms compared with 286 for Trump, and between 200 and 250 condos compared with 472 for Trump.

Carley said formal marketing will not begin until September, and construction will not start until there are sales agreements for about 40 percent of the units. He wants to break ground in March and finish in 2009.

Prices at the Fordham Spire must average $650 a square foot just for Carley to break even, sources said, making the project one of the most expensive in the city and approaching Trump's, where the prices are said to average $750 a square foot since marketing began. That translates, roughly, to condos valued at between $6.5 million and $7.5 million.

And local developers were skeptical of Carley's plan, citing escalating construction costs.

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How it stacks up

- 2,000 feet to top of spire, taller than the 1,776-foot Freedom Tower

- 920,000 total square feet, compared with 4.5 million for Sears Tower

- Up to 250 condos, compared with 472 for Trump's Chicago tower

- Condos would likely be valued between $6.5 million and $7.5 million

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Tallest building in North America proposed

A proposed hotel and condominium building on the lakefront would tower over other Chicago landmarks.

CHICAGO

Fordham Spire / Proposed

2,000 ft.

115 floors

Sears Tower

1,450 ft.

110 floors

Trump Tower / Under construction

1,360 ft.

92 floors

Aon Center

1,136 ft.

83 floors

John Hancock Center

1,127 ft.

100 floors

NEW YORK

Freedom Tower / Planned

1,776 ft.

82 floors

Note: Antennae are not included in a building's height. A spire may be considered an architectural component of the building and be included in the height. Renderings are not in proportionate scale. Ceiling heights may differ, accounting for numbers of floors.

Sources: The Fordham Co., Emporis