One's of Chicago's youngest landmark office buildings would be rehabilitated through a property tax incentive introduced today to the Chicago City Council.

The Inland Steel building, 30 W. Monroe St., would 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.

The $18.7 million rehabilitation project would include a sprinkler system upgrade and several energy efficiency improvements, including a partial green roof. The upgrades would help the building attract new tenants. It is currently 45 percent vacant.

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.

The Class L incentive, made available through the Cook County Assessor's Office, requires City Council approval. Council referred the proposal to committee.