If you create an Outlook group with all the 520 conference rooms, you can easily view all the conference room availability in the Scheduling Assistant. For how to use Scheduling Assistant click here /wiki/spaces/CCIIT/pages/293470209.
Step-by-Step
Click the contacts icon on the bottom of your Outlook bar
...
That's it! Now, when you are scheduling a new meeting, in the scheduling view simply write the name of the group you created as one of your attendees, and you can see all the conference rooms at a glance.
...