The author visited and studied megalithic sites all over Europe, the Near East and North and South Americas. By careful measurement and observation he illustrates astronomical alignments built in to these sites. Black and white photos and drawings abound. This is a clear, thorough and extensive survey of archaeo-astronomy. He misses some alignments that later work has uncovered, such as the Venus alignment at Newgrange (Uriel's Machine by Knight and Lomas), but this book does justice to an interesting field. A must read for people interested in the civilizations of pre-history.