stylistic:tone, quality:correction
Architecture

Most ancient Greek cities lay on or near hills, so seating was generally built into the slope of a hill, producing a natural viewing area known as the theatron (literally "seeing place"). In cities without suitable hills, banks of earth were piled up. At the foot of the hill was a flattened, generally circular performance space with an average diameter of 78 feet (24 m), known as the orchestra (literally "dancing place"), where a chorus of typically 12 to 15 people performed plays in verse accompanied by music. There were often tall, arched entrances called parodoi or eisodoi, through which actors and chorus members entered and exited the orchestra. In some theatres, behind the orchestra, was a backdrop or scenic wall known as the skené.

The term theatre eventually came to mean the whole area of theatron, orchestra, and skené.