From the Romans to the Raj, the Ottomans to the Incas, great empires have come and gone through the ages; but all have left behind extraordinary legacies, monuments, inventions and innovations that were so revolutionary that they changed the course of history. Bringing to life ten great empires, each episode visiting the ten most significant sites that defined their achievements and legacy; "Empire Builders" visits 100 historic sites, discovering how they were built, for what purpose, and what