Ley lines are alleged alignments of a number of places of geographical interest, such as ancient monuments and megaliths that are thought by certain adherents to dowsing and New Age beliefs to have spiritual power. Their existence was suggested in 1921 by the amateur archaeologist Alfred Watkins, in his book The Old Straight Track. The believers in ley lines think that the lines and their intersection points resonate a special psychic or mystical energy. Ascribing such characteristics to ley lines has led to the term being classified as pseudoscience.
Ley lines can be the product of ancient surveying, property markings, or commonly traveled pathways. Many cultures use straight lines across the landscape. In South America, such lines often are directed towards mountain peaks; the Nazca lines are a famous example of lengthy lines made by ancient cultures. Straight lines connect ancient pyramids in Mexico; today, modern roads built on the ancient roads deviate around the huge pyramids. The Chaco culture of Northwestern New Mexico cut stairs into sandstone cliffs to facilitate keeping roads straight. Additionally, chance alignments and coincidence are often cited as explanations that cannot be ruled out.