A man gets into the bathtub, the water overflows and he shouts “Eureka”. The man‘s name was Archimedes and he had discovered that he could measure the density of a body indirectly based on the amount of water displaced. His discovery, that buoyancy is equal to the weight of the water displaced, is still valid today. It even applies to cruise ships with more than 5000 passengers. Great Inventions examines the history of these giant ocean liners, what it takes to build a floating hotel complex and how the journey is continuing.