I just stayed there, and found two options for parking: there's on-the street parking below ground, on ?Columbus? that's metered. I'm not sure if it's free on Sundays. It's by the entrance to all the parking garages. Also, I parked for one night in the Millennium residences garage, and it was $25, so that's an option too. There was also a sign for an "early bird special," where it was a reduced rate if you parked by a certain time at that garage...