Ancient Greece: A land of gods, heroes, monsters... and very few roles for women beyond wife and housekeeper.
In other words, it's a pretty terrible place and time for a renegade student of Princess Celestia to find herself. But Sunset Shimmer is nothing if not determined and resourceful. She will bend this world to her will.
That's the plan, anyway. Given how the heliocentric model is still a few millennia away from wide acceptance, maybe she can settle for finding happiness.
Winner of the Sunset x Villain Period Piece contest.