This is the extraordinary story of how the quest to try to crack the mystery of the Megalithic Yard - an ancient unit of linear measurement - led to the discovery of compelling evidence pointing to the existence of an unknown, highly advanced culture which was the precursor to the earliest known civilizations such as the Sumerians and the Egyptians. There must have been a Civilization One. The authors show how this very precise unit of 82.966656cm, proven to have been used in the construction of thousands of megalithic structures in Britain and France, was derived from observing the rate of the spin of the Earth - based on a form of geometry that had 366 degrees to match the 366 rotations of the Earth in a year. They reveal how this is part of an integrated system, far more advanced than anything used today, which forms the basis of both the Imperial and the Metric systems. The ancient scientists understood the dimensions, motions and relationships of the Earth, Moon and Sun - they measured the solar system and even understood how the speed of light was integrated into the movements of our planet. The implications of these revelations go far beyond the fascination of discovering a super-science of pre-history: they indicate a grand plan which will have far-reaching theological ramifications!