"Narrator: A long time ago, people thought the world was flat, and if you sailed uncharted waters, you just might fall over the edge into space. This may sound strange to us now, but in those days, no-one knew what lay over the far horizon. What with pirates, and hurricanes, and sea-monsters to contend with, it's a very dangerous time. But in 1492, there appeared an Italian navigator. A man with the revolutionary idea. He thought the world was... square, and his name was... Christopher Columbus."