What was the motivation behind the development of Stonehenge over 1500 years? Was it a ceremonial site dedicated to the ancestors...a currently fashionable view? Was it a communal necropolis? An exercise in sophisticated geometry? A calendar for tracking the seasons and longer celestial cycles? A calculator for predicting eclipses? Perhaps at various times it was all these things? Now Professor Gregg has gone back to reassess the design of the site and discovered many startling and unexpected patterns. The same triangle and polygon geometry was used to scale monument features over the full 1500 year history. Feature dimensions and proportions reflect key cycles of the Sun and Moon as do stone counts. As a control the professor analyses the gear trains of the 2nd century BC, Antikythera astronomical computer, and finds the same, often prime numbers in play. Where the Antikythera device used rotating gears for its calculations, Stonehenge used fixed stones and rotating 'priests'. Remarkably the same numbers turn up in Greek and Egyptian numerical myths and Eurpean folk memories speak of dancing stones (or priests) and taboos on ordinary mortals counting or moving stones at megalithic sites. It also turns out that the geometry used and the astronomical cycles modelled have close connections to pi and phi, the Golden Section, in remarkable ways. Could it be that the designers of Stonehenge recognised these strange coincidences between earthly geometry, the great irrational numbers like phi and key celestial cycles? As above so below. Did these strange coincidences inspire the buildres to record them in stone and perhaps to worship, ceremonial and ritual there? Did they feel the gods were speaking to them? The professor also examines the case for the infamous 'megalithic yard' and finds much convincing new evidence for its existence including its close and simple scaling relationships of several established ancient metrics. These close relationships hinder the identification of which units were used at sites like Stonehenge. Underlying all these metrics the professor sees a possible origin in geodetic scaling. Remarkably at Stonehenge and many other ancient sites feature dimensions often are in simple fractions of seconds of arc. This occours at levels hard to attribute to chance. He concludes reluctantly, that at some early date, before the unification of Egypt, one or more cultures accuratley measured the size of the Earth. This geodetic measure was then used to calibrate primitive metrics based on human proportions...probably through early trade links. The professor concludes from all this material that our models of intellectual and scientific development are wrong and that we have greatly underestimated what can be done with simple technology as the astronomical knowledge of the Greeks, Babylonians and the Maya show us. Just how much have we forgotten?