In this episode of EMPIRE BUILDERS we explore ten sites that made history. In modern-day Istanbul, we visit Byzantium's greatest church, the Haghia Sophia; and, we see the Crusaders' greatest fortress, Crac de Chevalier in modern-day Syria. In Venice, St. Marks Basilica proves to be a showcase of the Venetian Empire at its peak. Together, through these great sites and others, we navigate the rise and fall of the great Christian empires of Byzantium, the Crusades and Venice.