Connected with this proscenium were the buildings belonging to the stage; these usually formed a structure several storeys in height, which enclosed the stage on three sides (compare Fig. 153) in the plan of the theatre of Dionysus (Fig. 150). The older walls belonging to the fourth century are sketched more lightly than the later restorations; here the walls of the stage, the actual _skene_, is the piece marked G. Z.; on the right and left were side wings (παρασκήνια), and these were terminated by the walls 12 and 13. The latest investigations of Dörpfeld prove that the stage of the theatre of Dionysus, constructed by the orator Lycurgus, had originally no fixed proscenium, but that a fresh wooden stage was constructed on every occasion. In later times they cut off a piece of the two side wings and fixed scenery between them. Several doors led from the tent to the stage; as a rule, there were three in the background, of which the middle one was the entrance of the chief actor, called “Protagonist,” and was supposed to lead either from a royal palace, or a dwelling, or a cave, according to the nature of the play; the door on the right was for the second actor, the one on the left had no special significance. We must not, however, regard these statements as universal. Probably there were usually three entrances to the stage, though in the theatre of Dionysus there is only a single door; but as the front was usually covered by some decoration, these entrances were not directly used, but the actors came through them into the narrow space between the wall of the stage and the decorations, and thence through the doors in the decorations on to the stage. The scenery of the background varied according to the nature of the action, and sometimes required several doors or entrances; sometimes there may have been no door at all, since the actors also had at their disposal the entrances by the side wings. These statements, therefore, only refer to certain plays, especially those tragedies in which the chief personage is a king; in this case, probably, the middle door was the one supposed to lead to the royal palace, and used, therefore, only by the protagonist, although we must not on that account suppose that he always came and went through this door, since the nature of the plays would of itself forbid this. Very often, too, a king appeared in the play whose part was an unimportant one, not given to the protagonist, and then, of course, the rule above quoted could not be observed.