Leonardo's Dream Machines

Renaissance artist Leonardo da Vinci may be best known for his paintings, but engineers consider him just as much a genius for the machines he designed that were years ahead of their time. This film narrated by Richard Denton documents the attempts of modern experts to build some of da Vinci's designs, including a massive crossbow with arms 70 feet across and a glider that he imagined more than four centuries before humans first took flight.