Chicago’s iconic architecture was blown up in fiery blasts, invaded by alien robots and parts of Michigan Avenue were reduced to rubble.  And Michael Bay is to blame.

“Transformers 3” began filming in Chicago on July 9 and ended Sept. 1, pouring $20 million into the local economy and providing at least 1,200 jobs, according to the Chicago Film Office.

According to the Chicago Transit Authority, the filming detoured 29 different bus routes throughout the summer and shut down parts of LaSalle Street, Michigan Avenue, Wacker Drive, Washington Street and Madison Street. Wabash Avenue parking was prohibited in many areas around the film set but generally, sidewalks remained open.

Prior to applying for a permit to film in Chicago, a future production must negotiate the logistics of what can be shot and where the filming will take place, and have solid plans to make it possible, according to the Chicago Film Office.

“They started those discussions with us as early as December of last year,” said Rich Moskal, director of the Chicago Film Office.

Producers and representatives visited the city shortly afterward, Moskal said. “This was all prior to a script even being formally written.  They had some concepts, and they had some treatments, but they really didn’t have the specifics yet.”

“Transformers 3” director Michael Bay visited Chicago in January and proposed some of the bigger feats, such as shooting on the Michigan Avenue Bridge

and LaSalle Street.

“We also knew it was going to be a big production, a big budget, high profile and that they had the resources necessary to do some of these things because closing Michigan Avenue is not an easy thing to do,” Moskal said.

Since filming ended recently, the specific finances for “Transformers 3” are unavailable as of press time. In comparison, “The Dark Knight,” shot in Chicago in 2007, was filmed  for 65 days, and the film’s production spent over $35 million in its stay.  Roughly $18 million  was spent to employ more than 900 crew members, 88 actors and 7,500 extras. Another $17 million was spent on nearly 800 local vendors, from film developing and lighting equipment to catering companies and hotels.

Joe Carpita worked as a second assistant camera operator with the crash cameras on “Transformers 3” for approximately three weeks this summer.

“It’s a little inconvenient if there’s a road closed on the weekend, but look how much money is being pumped into the economy,” Carpita said.

According to Moskal, the road closures were a minor complication compared to

the financial and intangible gains for the city.

“There’s an immediate financial benefit … and that’s the biggest reason why Chicago courts the industry,” Moskal said. Beyond finances, Moskal noted a film like this could raise the city’s international profile, as well as encourage tourism.

Some local businesses unable to stay open during filming were compensated. Others were able to function during street closures, allowing pedestrians and customers to pass through during shooting breaks.

“I thought the communication level [the production team] had was stellar,” said Jon Bartlett, general manager at the Hotel Monaco, which was impacted for two weekends when the streets were closed. “Yes, we received fair compensation.”

In 2007, “The Dark Knight” spent over $3.1 million on accommodations and over $1.1 million on location fees, both public and private.

The “Transformers 3” filming did not encounter many complaints or problems from the city, according to the Chicago Film Office.

“Overall, it was supportive; not to say people didn’t have their concerns,” Moskal said. “They needed assurance that customers would be able to get to their businesses. Solutions were found with pretty much everybody.”

The “Transformers 3” film set often drew attention because of pyrotechnics and stunts, as well as celebrity cast members Shia LaBeouf and Josh Duhamel.

“There were usually big crowds of people trying to see the robots,” Carpita said. The only negative responses he noticed were tourists getting lost due to detours and honking of horns.

The success of other movies and “Transformers 3” could lead the city to becoming a top player in the film industry.

“Chicago has been developing as a film production center, as a destination for Hollywood, dating back to ‘[The] Blues Brothers,’” Moskal said. “‘Transformers,’ and what we can anticipate as the great success of ‘Transformers,’ will not only

attract the attention of the general audience, but it’s bound to attract the interest of other filmmakers.”

A television show called “Ride Along” was recently picked up after a pilot episode and will be shot in Chicago, and in October, a film called “Contagion”, starring Matt Damon and Gwyneth Paltrow, will be directed here by

Steven Soderbergh.

“Chicago is going to shine as a place that is able to meet the challenge, and make it work,” Moskal said.