The Chicago City Council recently approved the landmark designation for the Old Chicago Main Post Office. Built in phases from 1921 to 1932, the 2.3-million-square-foot structure is located on the western bank of the south branch of the Chicago River in Chicago’s Near West Side. The building’s brawny nine-and twelve-story art deco design is the work of Chicago architectural firm Graham, Anderson, Probst & White, a successor to D.H. Burnham and Company.

The Old Chicago Main Post Office was constructed with a 40-foot-wide rectangular hole running through the center of the building, intended to accommodate a provision of the 1909 Plan of Chicago for a Congress Street extension from the South Loop to Chicago’s West Side. While various plans were floated for the extension in the 1930s, the space wouldn’t come into full use until 1955, when the Congress (now Eisenhower) Expressway was completed, connecting the Loop to the western suburbs.

The building’s main lobby sports lavish details like white marble and gold glass mosaics, but its original function was utilitarian in nature, with the majority of the spaces dedicated to feed conveyors, hoppers, mechanical tables, and chutes that supported a variety of mail sorting operations. The Old Chicago Main Post Office remained in operation until a modernized facility was completed in 1996, leaving the building vacant.

While the Old Chicago Main Post Office was added to the National Register of Historic Places in 2001, providing it with the opportunity to capitalize on Federal Historic Tax Credits, it is the local designation that provides a measure of protection from demolition and insensitive alteration, as a National Register listing is primarily used for planning purposes and is honorary. Local designation of commercial, industrial, and income-producing non-for-profit buildings also provides building owners with the opportunity to capitalize on Chicago’s Class L Property Tax Incentive, which reduces property levels for a 12-year period provided that half of the value of the landmark building is invested in an approved rehabilitation project.

According to the City of Chicago, the property’s owner, 601W Companies, is implementing a $292 million rehabilitation of the building as retail spaces and offices led by Gensler. The interior and exterior spaces will be comprehensively updated. The work will also repair existing rights-of-way for the Eisenhower Expressway as well as the Amtrak railroad facility located underneath the building.