Retired academic staff are entitled to free access, on request, to surface parking lots on weekends only, and a 50% discount on parking at Brooks garage. A pass must be obtained ahead of time from the Parking and Traffic Office located at 139 Louis-Pasteur, room 133, upon presentation of your UID card. Currently (2018), indoor parking at Brooks is $4.50 per hour, with a $17.00 daily maximum, but seniors (65+) pay half that amount. Unfortunately, Brooks tends to fill up very quickly in the morning, and space availability there doesn't ease up until later in the afternoon.
The agreement on parking between the APRUO and the Parking and Sustainable Transportation Office of the University (click here for the full text of the agreement) also covers parking privileges for retired professors in certain special circumstances (volunteer work, guest lectures, association meetings, etc.). For details on these special cases, see the text of the parking agreement.