What does the world look like from the moon? How do our bodies work? Is it possible for people to fly? Can I make a horse of bronze that is 8 metres tall? How can we have cleaner cities? All his life, Leonardo da Vinci asked questions. We know him as a great artist, but he was one of the great thinkers of all time, and even today, doctors and scientists are still learning from his ideas. Meet the man who made a robot lion, wrote backwards, and tried to win a war by moving a river...