Avalon is a historical-fiction high fantasy (and alternate universe) book about the Seleucid Empire forging an alliance with the Carthaginian Empire to reform the Persian Empire and conquer Rome and Albion. Where did I get the idea from? Well I was watching an episode of Game of Thrones (turn away now if you're terrified of spoilers), specifically 'The Door', the scene with the play.
This gave me the idea to write a history play, and that play slowly morphed into this story.