In the third and final part of Professor Allan Chapman's unusual look at the history of astronomical religion, he travels to Rome and Cairo, and argues that, contrary to widely-held prejudice, it was the Christian church which was largely responsible for the rise of scientific astronomy. Starting with the Ancient Greeks and Romans, Chapman examines how the classical world used the stars to tell the time and navigate the globe, but shows that, despite their scientific achievements, classical astronomers never completely shook off their archaic pagan beliefs of 'gods in the sky'. Chapman shows how medieval Christian astronomer priests knew that the world is round; they knew how big it is, and even how far away the moon is (as did the Greeks).