The orchestra in the Athenian theatre is mostly of very late date, and contains but few traces of the original structure. Our knowledge of the early Greek orchestra has to be derived from other sources. Before proceeding to discuss this part of the subject, it will be convenient in the first place to give a brief description of the existing remains in the theatre at Athens. The only portion of the old orchestra of Lycurgus which has been preserved is the gutter. This gutter, which was intended to drain off the water from the tiers of seats, ran immediately inside the border-line of the auditorium. It was made of limestone, and was about a yard in width. At the western corner it was 31 inches deep, but increased in depth all the way round to the eastern corner, where the depth was 43 inches. Here it made a sudden drop of about a yard, and then ran off in a south-easterly direction underneath the stage-buildings. It had no covering, except opposite the vertical passages, where it was bridged over with slabs of limestone. Apart from this gutter the greater part of the present orchestra belongs to the time of Nero. At this date considerable changes were made. The stage was probably pushed forward as far as the two corners of the auditorium. The orchestra, having been thus largely reduced in size, was covered over with the marble pavement which still remains. This pavement consists for the most part of rectangular slabs, placed in lines parallel to the stage. But in the centre there is a large rhombus-shaped figure, bordered with two strips, and paved with small slabs also of a rhombus shape. In the middle of the figure is a block containing a small circular depression, which was probably intended to receive an altar of Dionysus. At the time when the pavement was constructed, the gutter was also covered over entirely with slabs of marble, with rosette-shaped openings at intervals. Some of these openings have been preserved, and are indicated in the plan. At the same time a marble balustrade was erected in front of the first step of the auditorium. It is marked by the dark line in the plan. Most of it is still standing, and consists of marble slabs bound together by iron clamps, and 43 inches high. The purpose of the balustrade must have been to serve as a protection to the spectators in the front rows, when the orchestra was given up to gladiatorial combats or similar exhibitions. After these innovations of the Neronian period the orchestra seems to have been untouched until about the end of the third century A.D., when Phaedrus erected his new stage. It was then made water-tight, for the purpose of holding mimic sea-fights in it. The gutter was filled up, and the rosette-shaped openings closed. Traces of the pipes used for letting on and letting off the water for the sea-fight have been discovered in various parts of the building.