The ancient Greek theater was shaped by the literary evolution of the plays. Threshing floors, where the rural Dionysiac troups first held their feasts, constituted the early pattern of the round orchestra (playing area) in subsequent theaters. In the center of this orchestra was the thymeli, the altar of the god, demonstrating the origins of the theater in ritual. In the initial dithyramic assemblies, devotees stood around the threshing floor. In the theatre, the spectators’ seats filled the amphitheatric auditorium which was built into the natural slope of a hill and usually divided into two horizontal diazomata (sections) and many wedge-shaped kerkides (blocks of seats) the number of which changed according to the size of the orchestra. The tiers in the upper section were twice the size of those in the lower. The auditorium covered 2/3 of a full circle, making it necessary to build retaining walls to support the side sections. The seats were semicircular rows of steps. The first row had comfortable, throne-type seats with backs, places of honour. When women were permitted to attend a certain performance, then they sat in a separate section. The places in the upper diazomata were for foreigners. Slaves did not appear to have the right to attend performances.
The orchestra (playing area) was the soul of the theatre. All the other parts grew up around it, as its final circle was surrounded by the auditorium. The altar, which was right in the centre, had to be equidistant from all sections. The side doors haytheatre beside the retaining walls of the auditorium were called the parodoi, through which the spectators entered the theatre. The appearance of actors through these entrances was significant for the plot of the play: the public was aware of the convention that when an actor entered from the right-hand door, he was coming from the city; the use of the opposite door meant that he was arriving from some distant place. The members of the chorus always stayed in the orchestra, even later when a platform and stage buildings were added to its open side. There was a strict mathematical relationship between stage, altar and auditorium, which was related to the effort to perfect the acoustics.
With the creation of the stage, steps were built leading up from the orchestra to the lodge (platform), where the actors recited their parts. At the back there was a large wooden facade, movable and painted, which depicted an outdoor backdrop. This facade was always the same according to the play: in tragedy an official building was shown, usually a palace or temple; in comedy smaller, rural buildings tended to be used; in satyric drama, the scenery required a cave entrance. As the performances were held during the day, no artificial lighting was necessary, although there were various sound effects used, such as metallic containers full of water to increase the volume of the speeches, and pebbles were shaken around in bronze jars to sound like thunder . The technicians who wielded these vessels would either stand behind the scenery or along the sides of the platform, in the side-wings. In the stage building behind the platform, there were areas where the actors changed their masks and costumes and where these props were kept after the performance.
The architecture of the theater was perfected in the 4th century, the primary example being that of Epidaurus. But all around the Mediterranean, theaters of all sizes bring back echoes of ancient Greece.
In neighboring Rome, performances of drama began in the middle of the 3rd century at the Hippodrome, on movable platforms. Stern Roman senators were not particularly fond of free-thinking Greek plays, and thus the building of permanent theaters was expressly forbidden, until Pompey visited Mytilene and was so impressed by its stone theater that he built a similar one in Rome in 55 BC. But the all- powerful Senate forbade the building of seats, and for this reason the first spectators had to bring their own chairs. During the years that followed, given the influence of Hellenic education on Roman society, many theaters were built which differ in many ways from those of Greece.
In Roman theatres, the auditorium covered only half of a circle and the rows of permanent seats were initially intended only for senators. Later other rows of seats were added for minor notables, even though social differences were very strict. The upper sections filled with crowds. Above the last row of seats there was a covered portico around the entire semi-circle. The seats were raised well above the orchestra, since this area was frequently flooded with water for the presentation of mock naval battles, as Roman spectacles were gradually replacing classical Greek works of philosophical simplicity.
Another innovation was that in the place of the ancient Greek side entrances, boxes were built for the emperor on one side and the Vestal Virgins on the other. At the end.