A marvellous place! This room is inside the Oper in Vienna. If I remember correctly, after you climb up on the stairs, you turn left and then right.
This amazing room is the place where the emperor was welcoming his guests at the opera, that was ready to perform up there on the stage. They say that the emperor was welcoming his guests here, having a tea, then going inside, together with the audience. If he liked the play, the emperor stayed until the end. If he did not like the play, he was leaving the box seat and returning to this tea room, after the first play. For the people not to notice he was away, the emperor would return in the last act of the opera.
Thereâ€™s another story about this room. You can see in the right part of the picture that the room has a window. Most of the people that were coming to the opera were there to see the emperor first and then to watch the play itself. So the people were entering the building, checking if there is light in the emperorâ€™s tea room. If there was light => the emperor was here => they bought tickets for the opera. If the emperor was no light => the emperor was not here => they returned to their houses.