Ley lines (/leɪˈlaɪnz/) are straight alignments drawn between various historic structures, prehistoric sites and prominent landmarks. The idea was developed in early 20th-century Europe, with ley line believers arguing that these alignments were recognised by ancient societies that deliberately erected structures along them. Since the 1960s, members of the Earth Mysteries movement and other esoteric traditions have commonly believed that such ley lines demarcate "earth energies" and serve as guides for alien spacecraft. Archaeologists and scientists regard ley lines as an example of pseudoarchaeology and pseudoscience.
The idea of "leys" as straight tracks across the landscape was put forward by the English antiquarian Alfred Watkins in the 1920s, particularly in his book The Old Straight Track. He argued that straight lines could be drawn between various historic structures and that these represented trade routes created by ancient British societies. Although he gained a small following, Watkins' ideas were never accepted by the British archaeological establishment, a fact that frustrated him. His critics noted that his ideas relied on drawing lines between sites established at different periods of the past. They also argued that in prehistory, as in the present, it was impractical to travel in a straight line across hilly or mountainous areas of Britain, rendering his leys unlikely as trade routes. Independently of Watkins' ideas, a similar notion—that of Heilige Linien ('holy lines')—was raised in Germany in the 1920s.
During the 1960s, Watkins' ideas were revived in altered form by British proponents of the countercultural Earth Mysteries movement. In 1961, Tony Wedd put forward the belief that leys were established by prehistoric communities to guide alien spacecraft. This view was promoted to a wider audience in the books of John Michell, particularly his 1969 work The View Over Atlantis. Michell's publications were accompanied by the launch of the Ley Hunter magazine and the appearance of a ley hunter community keen to identify ley lines across the British landscape. Ley hunters often combined their search for ley lines with other esoteric practices like dowsing and numerology and with a belief in a forthcoming Age of Aquarius that would transform human society. Although often hostile to archaeologists, some ley hunters attempted to ascertain scientific evidence for their belief in earth energies at prehistoric sites, evidence they could not obtain. Following sustained archaeological criticism, the ley hunter community dissipated in the 1990s, with several of its key proponents abandoning the idea and moving into the study of landscape archaeology and folkloristics. Belief in ley lines nevertheless remains common among some esoteric religious groups, such as forms of modern Paganism, in both Europe and North America.
Archaeologists note that there is no evidence that ley lines were a recognised phenomenon among ancient European societies and that attempts to draw them typically rely on linking together structures that were built in different historical periods. Archaeologists and statisticians have demonstrated that a random distribution of a sufficient number of points on a plane will inevitably create alignments of random points purely by chance. Skeptics have also stressed that the esoteric idea of earth energies running through ley lines has not been scientifically verified, remaining an article of faith for its believers.