One's of Chicago's youngest landmark office buildings is being rehabilitated through a property tax incentive approved today by the Chicago City Council.

The Inland Steel building, 30 W. Monroe St., will save more than $5 million in property taxes through the Class L incentive, which encourages the preservation and rehabilitation of landmark buildings by lowering the cost of property taxes over a 12-year period.

Already underway, the $18.7 million rehabilitation project includes a sprinkler system upgrade and several energy efficiency improvements, including a partial green roof.

Designed by Chicago architects Skidmore, Owings & Merrill as the corporate headquarters for the Inland Steel Company, the 19-story building was the youngest high-rise to receive the city's landmark honor at the time of its designation in 1998.

Constructed in 1954 in the International Style, its external structural columns and the consolidation of its building systems in an adjacent tower have made it one of the defining commercial high-rises of modern architecture, according to the Commission on Chicago Landmarks. It is currently owned by a real estate investment group.

Coordinated by the Chicago Department of Land Use Planning's Historic Preservation Division on behalf of the building's owners, the Class L incentive is made available by Cook County Assessor's Office.