The easiest place to park is in the Tower Self Park. Its entrance is on Franklin right across from the Willis Tower. Call (312) 782-5570 for rates.
Alternative parking options include:
InterPark Traders Garage
329 S. Franklin
24 hours. Call for rates.
System Parking Lot
321 S. Wacker Dr.
Call for rates.
This is an open lot that can accommodate oversized vehicles.