We now come to the interior of the auditorium. The boundary between the auditorium and the orchestra is denoted by the dark line in the plan. It will be observed that in the theatre of Dionysus the inside boundary of the auditorium consists of a semicircle with the two ends prolonged in parallel straight lines. This was not the plan usually followed in Greek theatres. In most of the later theatres the two ends of the semicircle were prolonged in the same curve as before, so that the inside boundary of the auditorium formed about two-thirds of a regular circle. The effect of this arrangement was that the spectators sitting at the extremities of the two wings faced towards the centre of the orchestra, and away from the stage. Nor is this surprising. It was previously pointed out that in Greek theatres, where the choral and musical contests greatly outnumbered the dramatic, the orchestra was always the most important part of the whole building. But the arrangement adopted at Athens, of prolonging the two ends of the semicircle in a straight line, had the advantage of giving the spectators in the wings a much better view of the stage. The same plan was also adopted in the theatre of the Peiraeeus, and in the theatres of Assos, Acrae, and Termessos. At Epidaurus and Magnesia a third plan was pursued, differing from both the above. The two ends of the semicircle were prolonged, not in a straight line, nor yet in the same curve as before, but from a new centre, and with a longer radius, so that while they converged to a certain extent, they did not converge so much as in the ordinary Greek theatres. This arrangement, which may be regarded as a compromise between the other two, is perhaps the most beautiful of them all. It is apparently recommended by Vitruvius, though the passage in which he refers to it is extremely ambiguous and has been interpreted in various other ways.[337]