Revisions to the Art Institute's expansion plan, originally approved in 2004, were recently endorsed by the city's plan commission. The third floor, visible from Michigan Avenue, will add a restaurant and sculpture garden overlooking Millennium Park to the north. The third floor will be accessible, with no charge, by an escalator from the Monroe Street side of the building, now 693,000 sf. The addition, designed by architect Renzo Piano, will add nearly 300,000 sf to the building.

The addition is expected to be completed in 2009. Art Institute officials say expansion is needed to hold the more than 270,000 objects in its collection.

The Art Institute of Chicago has embarked on a fund-raising campaign to raise money for the addition, as well as upgrading the heating, air conditioning and ventilation system in the entire building. In addition to $200 million in construction, the Art Institute hopes to collect another $87 million to support operations in the new portion of the building.