City of Cambridge has 2 municipal garages and 9 Off-Street Parking Lots.

First Street Garage
Located in East Cambridge across from the Middlesex Court house (map)
Open 7 days a week
Entrance on Spring Street
Rates:   $2.00 first hr.
             $1.00 2nd 
             $2.00/hr thereafter
             $20.00 daily maximum
             $5.00 night rate, enter after 4 pm, depart by 6 am.
             $5.00 weekend daily maximum

Green Street - Franklin Street Garage
Located in Central Square at the corner of Pearl Street and Green Street  (map)
Green Street Artwork   (Link)
Open 24/7
Entrance on Green Street
Rates as of March 1, 2009:
             $  1.50    1hr 
             $  3.00    2 hrs
             $  4.50    3 hrs
             $  6.00    4 hrs
             $  7.50    5 hrs
             $  9.00    6 hrs
             $10.50    7 hrs
             $12.00    8 hrs
             $13.00    daily maximum 
             $ 6.00   night  rate, enter after 6 pm, depart by 8 am.