What is the name for the walkable area above a stadium?
Solution 1:
The general term you might refer to is Catwalk, but there must be a specific term for stage.
Solution 2:
Above the stage is the Rope Loft or Fly Loft. To day it's usually referred to as The Grid. The working/walking areas are usually referred to as The Bridge. If you say "Up on the grid" riggers and techs will know what you're talking about.
Also see: http://en.wikipedia.org/wiki/Fly_system