Mysterious Stonehenge has been a magnet for theorists of every stripe for centuries. This new interpretation, by a historian of science (Groningen Univ., the Netherlands), argues that it was both an astronomical observatory and a map of the heavens. Actually, North's net is spread much wider than the title suggests. He begins with a discussion of the structure and orientation of long barrows (or mounds) and ends up examining almost every class of prehistoric megalithic monument on the British Isles as well as some in Western Europe. North has little patience with the idea that the megalith-builders were crude workmen, citing some of the better-preserved monuments that have precise alignments of various points with certain fixed stars. He finds a historical progression from the early long barrows to the later stone avenues and rows, with henges (circular enclosures first made of wood, then stone) the culmination of the tradition. Stonehenge itself evolved over some 2,000 years, and North provides a complete inventory of its components and reconstructs the various stages of its growth. The sight lines through the stone rings are carefully diagrammed, and various astronomical relationships spelled out. Finally, the author brings together his various themes in a discussion of the astronomically based rituals and beliefs he feels we can deduce from the evidence he has compiled. The wealth of detail here, combined with copious diagrams and calculations, is likely to overwhelm the reader who is not familiar (at least through other books) with the monuments under consideration. And while North pays due homage to folklore and other colorful accretions to the subject, his highly technical approach makes this a book many casual antiquarians are more likely to skim than read. An important contribution to the literature of this fascinating subject, then, but more for the specialist than for the common reader.