As you probably already know, walls, ceilings, roofs, etc. are all system families that can only belong to a Revit Project File. Follow the following steps to see these System Families.
1. Open Revit
2. Be sure that you have installed the AVAIL Browser for Revit Addin
3. Once open, select the .RVT file from within the AVAIL Desktop
4. Back in Revit, you then can see the Families, View, Sheets, etc.
Note: All of these steps can be done from within the AVAIL Browser for Revit as well.