The ancient city of Persepolis – in the mountains of Iran – is the capital of the first world empire, Persia. What can it reveal about the scale of this imperial powerhouse? Iranian archaeologist Ali Asadi investigates the ruins to reveal magnificent palaces, halls, and military quarters. How do the Persians conquer most of the known ancient world? And how do they control it for over two centuries? Using stunning CGI we restore Persepolis to its former glory, unearth engineering marvels that span for thousands of miles, and uncover brand-new inventions that revolutionize the world, to discover the secrets of ancient Persia.