In the last programme in the series, John Romer tells how the Byzantium empire finally crumbled. Already weakened by the ravages of rogue Crusaders it succumbed to the invasion of the Ottoman empire of Turkey and the Christian centre of the world became the Islamic city of Istanbul. The scattered refugees took their art and culture worldwide, including Florence, Rome and even Romania to give the world a lasting artistic and cultural legacy that is the link between ancient Rome and Greece and the modern world.