Where was the arena stage originated?

The arena stage, also known as "theatre in the round," originated in ancient Greek theatre, where performances took place in open-air amphitheaters with a circular playing space surrounded by spectators. This design allowed for a more intimate and immersive experience, as the audience was seated on all sides. The concept was later revived in the 20th century, particularly in the works of influential theatre companies and experimental playwrights. Today, it remains a popular staging format in contemporary theatre.