Newgrange is considered the most complex megalithic site in the world. It is Ireland's most visited monument with around 250,000 visitor's a year. This book delves into the astroarchaeology of Newgrange and the Boyne valley alongside the Loughcrew and Carrowkeel cemeteries with astonishing revelations. This book contains new research and evidence that suggests Newgrange was aligned also to Sirius as a crude precessional calculator. Newgrange it seems was the pinnacle of a theme of passage grave cosmology running throughout Ireland. Knowledge of Precession of the Equinoxes is inherent in the passage graves of Ireland a fact that has never been explained nor addressed until now.