What is the setting of Oedipus Rex?

The setting of Oedipus Rex is the steps in front of the royal palace at Thebes.  This play adheres to Aristotle's unity of place, meaning that all the action takes place in just one setting; his unity of subject, meaning that there is just one main story and not little stories of lesser importance in addition to the main one; and his unity of time, meaning that all the action takes place within a 24-hour frame.  Oedipus first meets the Chorus out on the steps, and they are bemoaning the terrible state of things in Thebes when the play begins.  Oedipus has already sent Creon, his brother-in-law, to the oracle at Delphi, and Creon returns (during the play) in order to report what the oracle has said.  Anything that does not occur on the steps, such as Jocasta's eventual suicide, which takes place indoors, must be reported by a messenger, and anyone who is needed to corroborate a story or provide details must be brought to the palace steps to speak.