Definition: In general, the theatron was where the audience of a Greek tragedy sat to view the performance.
A theatron could refer to the place where spectator looked at sacrifices, dances or theatrical performances. There is debate as to whether early Roman theatres had seats. A theatron came to refer specifically to semi-circular, tiered, stone seats for viewing performances.
Examples:
In Cassius Dio's Epitome 68.27.3, theatron is used to refer to a gallery constructed to allow spectators to look down into a pit of vapors.Source: "The Nature of Hadrian's Theatron at Daphne," Richard H. Chowen. American Journal of Archaeology Vol. 60, No. 3 (Jul., 1956), pp. 275-277

