The ancient Greeks built open-air theatres where the public could watch the performances of Greek comedy, tragedy, and satyr plays. They then exported the idea to their colonies throughout the Aegean so that theatres became a typical feature of the urban landscape in all Greek cities. The Romans continued and expanded on the concept, added a monumental backstage, and generally made the structure more grandiose. The large semi-circular structures, still with their excellent acoustics, are visible today at many archaeological sites, and several of them remain in use not only for modern concerts and performances but also for festivals of ancient Greek drama.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/895/greek-theatre-architecture/.