What is closet parking? What are parking prices?

Everything in Chicago is expensive. Take a ride share to the museum and avoid parking downtown

I don't know about parking as I used uber.

The valet parking at the museum is 28$. Street parking has 3hour limit and cost 6.5$ an hour. Your best option is the millennium lakeside garage. It is the closest to museum and you can reserve online too. Online saves you a few dollars.

I used spot hero app and found one spot at grand park South entrance (right between symphony hall and the art institute) for $10 for 12hrs. Is an underground parking lot and very safe

I strongly suggest using the spot hero app for closest parking with the best rates.