This book provides the first comprehensive, easy-to-read, and up-to-date account of the fascinating discipline of archaeoastronomy, in which the relationship between ancient constructions and the sky is studied to gain a better understanding of the ideas of the architects of the past and their religious and symbolic worlds. The book is divided into three sections. The first section discusses in detail the fundamentals of archaeoastronomy, including the celestial coordinates, the apparent motion of the sun, moon, stars, and planets, observation of celestial bodies at the horizon, the use of astronomical software in archaeoastronomy, and current methods for making and analyzing measurements . The second part explores the past relations between astronomy and people, power, the afterworld, architecture, and landscape The final section reviews what archaeoastronomy can now tell us about the nature and purpose of such sites and structures as Stonehenge, the Pyramids of Giza, Chichen Itza, the Angkor Temples, the Campus Martius, Machu Picchu and the Valley of the Temples of Agrigento. Additionally, it provides a set of exercises that can be performed using non-commercial free software, e.g., Google Earth and Stellarium, and that will equip readers to conduct their research. This book is an ideal introduction to what has become a wide-ranging multidisciplinary science. This newly revised edition includes the most recent research on Stonehenge, ancient Japan, and other sites worldwide.