No ticket is required.
The Pier is free, like a mall
You have to pay for parking and some things require tickets. You'll definitely have to bring some money if you want to have a good time.
No tickets needed, you can just walk right on! If you drive, you'll need to pay for parking.
No tickets for navy pier needed
You don't need tickets for the Pier itself, but there are some attractions which require tickets, and you can get them at the attraction (the ferris wheel, the IMAX, the children's museum, etc).
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