Angelique Sallas, walking down Michigan Avenue on her way to work Thursday morning, stopped in her tracks in front of the Wrigley Building and stared in disbelief at the bovine vision before her.

"What is it?" she asked.

"It's a cow," said Barbara Karklins, an employee of the Wrigley Building who was also staring at the five life-size fiberglass animals standing on the sidewalk. "Actually, it's a whole herd," Karklins amended.

The sudden appearance of the cows on Michigan Avenue--among some 300 that will invade the city this summer--had absolutely nothing to do with April Fool's Day, though it was a nice coincidence. But the tale of how the whimsical sculptures happened to appear in an area more commonly associated with pigeons and the occasional rodent does have a certain surprising quality--as well as a larger artistic purpose.

It seems a member of the Greater North Michigan Avenue Association on a trip to Zurich last year was so taken with a similar public art project--fitting in Zurich because it celebrated the Swiss alpine cow--that he decided it would be good for Chicago too. The City's Department of Cultural Affairs agreed and is now riding herd on the project.

So it is that hundreds of the molded sculptures--to be decorated in a variety of fanciful styles by notable local artists--will be displayed along Michigan Avenue from Oak Street Beach to the Museum Campus. In October, some of the cattle will be auctioned off to benefit charity.

Almost 240 artists, including Ruth Duckworth, Ed Paschke and Helmut Jahn, have expressed interest in designing a cow.

Officials at the Wrigley Building, 410 N. Michigan, were among the businesses to buy cows, which were delivered Thursday, as yet undecorated. The scene stopped dozens of people as delivery men Chris Uphues and Rick Hards carried the white 40-pound sculptures into the building one at a time.

The process repeated itself inside as word spread and workers in the building rushed to the lobby for a peek. After being loaded into a freight elevator, the cows disappeared, not to be seen again until this summer's planned exhibition.

"I am greatly looking forward to the cows. I think it's whimsical, I think it's fun. I think people will enjoy it in the summertime," said Wrigley Building general manager Diane Allen.

She would not comment on how the five cows purchased by the Wrigley Company--for $3,500 apiece--will be decorated, or by whom. Cows will go for up to $11,000, depending on the reputation of the artists, who are being paid for their work.

For now, the concept evokes a little skepticism.

"It's a little unusual, to say the least," said Abra Huskey, 22, of Lake Forest, who happened by as the Wrigley Building's herd was unloaded.

Still another pedestrian, Bob Hanley, 62, a retiree living on the Near North Side, said he liked the notion of displaying the sculptures.

"That's a good idea, it really is," Hanley ventured.

Although cows also have been taken to other downtown businesses or area art studios, about 140 cows remained in storage Thursday on two floors of the Page Brothers Building, 191 N. State St.

Those cows are still waiting to be adopted by businesses and individuals, said city Department of Cultural Affairs project coordinator Nathan Mason. Mason said he was expecting a final shipment of 106 cows from Zurich next week, including six already decorated by Swiss artists.

While most of the molded cattle are being underwritten by private agencies and individuals, the city has reserved 20 to be painted by Chicago high school students at Gallery 37 this summer. In addition, 10 other cows designed by high-profile Chicago artists are being sponsored by the city for $4,000 each, although those sponsorships can be taken over by private interests for $11,000 apiece.

Among the high-ticket "concept cows" detailed by Mason is a solar-powered cow designed by Chicago artist Tom Czarnopys; an electrically wired cow from Jahn, the designer of the Thompson Center downtown; and a bright red design by Paschke in homage to the Chicago Bulls. Common proposals by other artists are cows decorated with cloudscapes, sky images, and floral patterns.