If you could go back to ancient Greece or Rome, what could you offer them? [I Like History]
You can't bring technology or any possessions with you. Assume that you magically have learned to be fluent in the language, and you simply show up, dressed in appropriate clothing.
With centuries of history and experience to draw on, what difference could you make when you talked to people from that era?
You do not suddenly get to be emperor. You are just a citizen.