Ley lines (/le?/) are straight alignments drawn between various historic structures 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.