Whether you're driving to the Millenium St. Louis or staying elsewhere and planning to drive in each day, here are a few tips on parking:
An enclosed parking structure, operated by InterPark, is located directly across the street from the hotel on South 4th Street.
Parking for hotel guests is $18 per day. You can come and go as you please with just the swipe of your room key. Guest parking is in the lower level of the structure - look for the sign "Millenium Hotel Parking."
Just driving in for the day? The same structure houses parking for everyone else. There's a $5.00 Early Morning Special if you arrive before 9:00 AM and leave between 2:00 and 6:00 PM. Beyond that, regular rates apply - a 12 hour day will cost you $18.00.
If you're really looking for a bargain, there's an open-air lot, operated by Central Parking System, located directly behind the InterPark structure on South Broadway. It sits between Busch Stadium and the Hilton Hotel (Clark & Walnut). You can park all day for $5.00 after leaving your money with the attendant or in a numbered slot if no one is on duty. (Note: this lot was developed after Google Map image in the link was taken.)