Middle Age

To our medieval forebears the world could appear mysterious, even enchanted. Sightings of green men, dog heads and alien beings were commonplace. The world itself was a book written by God. But as the Middle Ages grew to a close, it became a place to be mastered, even exploited.

Al-Khalili travels to northern Syria to discover how, a thousand years ago, the great astronomer and mathematician Al-Biruni estimated the size of the earth to within a few hundred miles of the correct figure. He discovers how medieval Islamic scholars helped turn the magical and occult practice of alchemy into modern chemistry. In Cairo, he tells the story of the extraordinary physicist Ibn al-Haytham, who helped establish the modern science of optics and proved one of the most fundamental principles in physics - that light travels in straight lines. Prof Al-Khalili argues that these scholars are among the first people to insist that all scientific theories are backed up by careful experimental observation, bringing a rigour to science that didn't really exist before.

Physicist Jim Al-Khalili travels through Syria, Iran, Tunisia and Spain to tell the story of the great leap in scientific knowledge that took place in the Islamic world between the 8th and 14th centuries. Its legacy is tangible, with terms like algebra, algorithm and alkali all being Arabic in origin and at the very heart of modern science - there would be no modern mathematics or physics without algebra, no computers without algorithms and no chemistry without alkalis. For Baghdad-born Al-Khalili, this is also a personal journey, and on his travels he uncovers a diverse and outward-looking culture, fascinated by learning and obsessed with science. From the great mathematician Al-Khwarizmi, who did much to establish the mathematical tradition we now know as algebra, to Ibn Sina, a pioneer of early medicine whose Canon of Medicine was still in use as recently as the 19th century, Al-Khalili pieces together a remarkable story of the often-overlooked achievements of the early medieval Islamic scientists.

Dan Snow uncovers the lost Vikings in America with space archaeologist Dr Sarah Parcak. Sarah uses satellites 383 miles above the earth to spot ruins as small as 30cm buried beneath the surface. As Sarah searches for Viking sites from Britain to America, Dan explores how they voyaged thousands of miles when most ships never left the shoreline. He also tracks their expansion west, first as raiders and then as settlers and traders throughout Britain and beyond to Iceland and Greenland. In North America they excavate what could be the most westerly Viking settlement ever discovered.

Dr. Thomas Asbridge explains how in the thirteenth century, after almost two hundred years of Holy Wars, the titanic conflict between Christianity and Islam, known to history as The Crusades, reached a decisive and shocking conclusion – a chapter that despite its drama has been virtually forgotten. He explains how, in the end, the fate of the Holy Land was decided not on the hallowed ground of Jerusalem, but in Egypt; and how the ultimate outcome of the Crusades was dictated not by Christians, but by the Mongol successors to Genghis Khan, and by a Muslim slave – a fearsome warrior whose story is now all but lost to western history.

The most famous – and perhaps most misunderstood – episodes in the epic history of the Holy Wars that are known to history as The Crusades – the clash between Richard the Lionheart and Saladin. In July 1192, Richard the Lionheart stood poised for a strike on Jerusalem, while Saladin – mighty sultan of Islam – readied his troops inside the city, preparing for the inevitable attack. During a year-long campaign across Palestine, these two legendary leaders had fought each other to a stand-still. Thousands had perished, appalling atrocities had been perpetrated on both sides. And now they faced each other in a battle for their sacred objective.