The structure will be big enough to hold eight football fields and cost more than $500 million to build, but it would employ no more than about 75 people, sources told Crain's Chicago Business. In contrast, the construction project may employ about 500 people.

Microsoft, based in Redmond, Wash., is building Internet infrastructure around the United States to compete more effectively with Google's and Yahoo! Inc. (NASDAQ:YHOO)'s search engines, the report said. Microsoft also wants to provide more Web-based services.

Crain's said the data center will house thousands of computer servers to process Internet activity and network services.

The report said it is not known whether Microsoft plans to lease or own the building.