That’s the tech booth at the back. People really would hang over the stairwell and wait for a director or stage manager.
The house is technically accessible, via an old and extremely rickety elevator that’s operated by continually holding a push button and praying. The stage, sadly, is not accessible, but one of the theatre’s longest-serving managers has multiple sclerosis and one of my happiest memories was lifting him up onto the stage for a bow on a closing night. I have been stuck in the elevator, however, many times–it requires wiggling of a nail to get the cabin unstuck on the way down. Very much in keeping with the spirit of the place.