Sun dials are probably the oldest instruments for measuring time, and around 3500 BC Babylonian and Egyptian astronomers developed water clocks. In all the many years of time measurement there have been many milestones, important developments which made their mark. To choose the most important milestones is therefore an impossible mission. And what are milestones? Iconic watches? Crucial moments? For this list we have chosen the former… Five immortal TAG Heuer lines – a brand that is always trying to achieve the most accurate time measurements.