You can just turn up and have a look around yourself. If you want to know more about the history of the place though, it's worth paying for a tour. You can buy tickets online.
The ground floor is open to the public during the work week.
Yes
Very pretty. A Chicago landmark. You can either show up on the ground level either pay for a tour (recommend option)
Very pretty and free on the ground level.
It is indeed pretty and you can walk right in, at least on weekdays.
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