It’s always free to go by the famous sites at Millennium Park. Snap a selfie with the silver Cloud Gate sculpture (AKA The Bean) and spend some time exploring the surrounding park. Get in some steps while walking around, or seek out specific sites in the area. The Jay Pritzker Pavilion often hosts free music and cultural performances, and the Boeing Galleries have outdoor art sculptures to view. Or just splash around Crown Fountain to cool off on a hot day.