Richard Hammond visits a building described as the 'greatest of our time' - the Guggenheim Museum, Bilbao, Spain - to find out which engineering connections made this iconic building possible. A visionary architect transformed a decaying city into a vibrant tourist hub with his futuristic building, but it would not have been possible without a volcano, an egg, Sir Walter Raleigh, a surveyor's trundle wheel and a Cold War Russian submarine.