An exposed Cloud Gate, better known as The Bean, hangs in a framed photo in the Harold Washington Library Center, its crisscrossing steel innards waiting for the final loose skin that will complete the structure.

The photo is one of 42 unfinished Millennium Park monuments lining the walls for the Chicago Public Library’s new exhibit, “Building an Icon: Construction Photographs of Millennium Park.”

The photos were taken over the course of the construction of Millennium Park along with over 5,000 others. They were donated to the library’s special collection by the company that oversaw Millennium Park’s construction, U.S. Equities Realty. The collection shows the entire process from concept to completion of Cloud Gate, Crown Fountain, Jay Pritzker Pavilion, BP Pedestrian Bridge, Millennium Monument and Lurie Garden.

Senior Archival Specialist Morag Walsh curates the exhibit, which runs until Jan. 17, 2010. She said she had to narrow the collection down to the 42 photos currently in the library’s Congress Corridor. Photographers and construction companies documented every aspect, from the Crown Fountain’s architectural models to the water feature test in Concord, Ontario. The entire construction of the fountain comprises more than one-fourth of the collection.

Walsh said the photos were initially donated for research purposes, but she found them so stunning she felt they should be displayed. The goal of the exhibit is to quickly give people an inside peek at the complex Millennium Park structure like Cloud Gate, Walsh said.

“It’s such a huge sculpture, the engineering that was involved, rolling the steel plates,” Walsh said. “That was like science fiction to try and get that done.”

Walsh said her favorite photo hanging in the exhibit is of a child joyfully playing in the water in front of one of the fountains. It changes on a daily basis though, and if she did another exhibit, she could choose another 42 photos that were just as rich and stunning, she said. Prints of every photo in the collection can be found in the library’s reading room or online under their digital collections section. Funding for the exhibit and prints was provided by the Gaylord and Dorothy Donnelley Foundation.

Edward Uhlir, Millennium Park, Inc.’s executive director, said the hardest part of the actual construction of Millennium Park was coordinating all of the different companies who worked on the project.

Uhlir said a total of three landscape architectural firms and eight different architectural firms were involved. That’s not counting the contractors. He said there were about 10 different general contractors and multiple subcontractors for every one of the park’s complex projects.

The project started in 1998 at the behest of Mayor Richard M. Daley. The area where the park now sits used to be 16 acres of exposed parking and railways, an eyesore and the site of many drug deals, Uhlir said. The other goal of the park was to provide a new home for the Grant Park Symphony Orchestra and Grant Park Chorus, which had been playing at the Petrillo Music Shell since 1978 and needed a better stage. Construction started in 1999 and the park officially opened in July 2004.

The Cloud Gate sculpture was dedicated in March 2006 after the park opened. The final step for its completion involved grinding out imperfections in the sculpture’s surface with a 15-pound belt sander, leveling out the seams between the welded plates and then rubbing out the fine scratches left by the belt sander. Photos of the final polishing are also in the photo collection.

Both Uhlir and Walsh said one of the things they remember was standing inside The Bean before it was sealed. Uhlir’s name is written on the inside, next to photographer Anish Kapoor’s name.