Curtain Walls in Revit are strictly a Family of the Walls Category. Then you have Types for each type of Curtain Wall. What if you want to select all Curtain Walls at once? You can’t multi-select types in the Project Browser to do this, but…

You can make a suitable Schedule to do it. Here’s how:

  1. Make a new Wall Schedule
  2. Only add the Family data field
  3. In Sorting / Grouping tab, Sort by: Family and untick ‘Itemize every instance’
  4. Now, in the schedule, click inside the Curtain Wall cell, and
  5. Use Highlight in Model to select them all

You could then use Save Selection, or Temporarily Isolate Elements in View, depending on what you want to do next.