We were at Marty's Shrine for only a little while, but we were lucky enough to see the changing of the guards. Black boots with white laces, gold braids and trims, white uniforms an white metal hats. These marching guards were to replace the guards that we had seen on duty back at the gate.
I believe the changing of the guards is done on the hour by active military personnel. Standing for an hour and not moving would be terribly boring, though I guess they get to look at all us tourists walking past.