Ley lines were first suggested to the general public by an amateur archaeologist named Alfred Watkins in the early 1920s. Watkins was out wandering around one day in Herefordshire and noticed that many of the local footpaths connected the surrounding hilltops in a straight line. After looking a map, he saw a pattern of alignment. He posited that in ancient times, Britain had been crossed by a network of straight travel routes, using various hilltops and other physical features as landmarks, needed in order to navigate the once densely-forested countryside.
Watkins' ideas weren't exactly new. Some fifty years before Watkins, an archaeologist named William Henry Black suggested that geometric lines connected monuments all over western Europe.
The idea of ley lines as magical, mystical alignments is a fairly modern one. One school of thought believes that these lines carry positive or negative energy. It is also believed that where two or more lines converge, you have a place of great power and energy. It is believed that many well-known sacred sites, such as Stonehenge, Glastonbury Tor, Sedona and Machu Picchu sit at the convergence of several lines.
There are a number of academics who dismiss the concept of ley lines, pointing out that geographic alignment doesn'€™t necessarily make the connection magical. After all, the shortest distance between two points is always a straight line, so it would make sense for some of these places to be connected by a straight path. On the other hand, when our ancestors were navigating over rivers, around forests, and up hills, a straight line might not have actually been the best path to follow. It is also possible that because of the sheer number of ancient sites in Britain, that the "alignments" are simply chance coincidence.