Wikipedia states: "Oakbrook Center is an upscale super-regional shopping center located near Interstate 88 in Oak Brook, Illinois. It was originally opened in 1962. Managed and co-owned by General Growth Properties, it is the second largest shopping center in the Chicago area, by gross leasable area."
This photo was sent in by CTTF, who adds: "When Oakbrook Center first opened, it was the largest outdoor mall in the nation - a title it still holds today. It has just been recently renovated now with LED lighting and new fountains. This photo is from the restroom below the main concourse of the mall."