Flying UA to ORD. Do not know which terminal it would use. Have 5 nights in Chicago July 1st to 6th. Stay at Radisson Blu by the Millennium Park.

Plan to take advantage of the BofA Museum on Us program to visit the Alder and Shedd on Sat and then Art Institute on Sun.

Plan to take the CTA train to town.

I understand that now it is on Ventra card system, you either buy a regular Ventra card and then load a Travel Pass to the card, or buy the 1-day pass from the Ventra machine.

If the Ventra has no expiration date then we could pay $5 for the card, then buy the 7 day pass which is $28, provided I do not lose the Ventra after trip.
Or we could just buy the 1-day Ventra pass as we see fit.

Question is where to buy these at ORD terminal(s)?

Thanks for help.