Old Chicago Main Post Office back on the market

CHICAGO (WLS) -- Chicago's old Main Post Office building is on the market again.

The building's owner is looking for an investor/co-developer or a potential buyer, according to the owner's hired brokerage firm.

The building will officially be listed next week, though no price has been established, the firm said.

The building, which has been vacant since 1995, went up for auction in 2009.

In 2013, the Chicago City Council approved plans to transform the 2.7 million square-foot structure into a new residential, commerce and office space as part of Project Marvelous. The projected cost of the development's first phase was over $1 billion.