How do you predict eclipses at Stonehenge? Why do the Carnac alignments follow geological fault lines? Was Avebury intentionally sited precisely one seventh of a circle down from the north pole? Why are so many stone circles egg-shaped or flattened? What is the meaning of the designs in ancient rock art? Do you really have to wait nineteen years to visit the remote site of Callanish? What were the ancients up to? These are our oldest buildings, our first messages, our earliest visual art. With eight authors, and packed with detailed information and exquisite rare illustrations, Megalith is a timeless and valuable sourcebook for anyone interested in prehistory.