The "Montclare JoAnn Thompson" is named after the late longtime alderman for the Englewood neighborhood.
Lawmakers, along with Mayor Lori Lightfoot, celebrated the grand opening with a ceremonial ribbon cutting Wednesday.
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The new building has a number of amenities, including a fitness center, and a beauty and barbershop.
It offers affordable housing to people 62 years old and older, which is something the mayor said is imperative.
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The eight-story building is located at W 63rd Street and S Green Street and has 102 one-bedroom units.