New age practitioners, such as psychics and dowsers, use ley line grid maps to delineate spiritual or magnetic vortexes that are believed to aid in healing or focus energy. Those with more mundane focus find locating ley lines on maps to be an interesting hobby.
Ley lines are invisible connections between important landmarks, whether ancient spiritual sites, such as Stonehenge or burial cairns, or physical topography, such as prominent mountains or forests. In 1925, Alfred Watkins published "The Old Straight Track," in which he explained his theory that ancient man created pathways for trade and transport along naturally occurring lanes. Straight Track clubs in Britain helped Watkins locate ley lines, a pastime that faded with his death in 1935.
Spritual seekers in the 1960s rediscovered the idea through John Mitchell's 1969 book "The View Over Atlantis," in which Mitchell espoused the theory that ancient man connected these paths to focus mystical energy. The energy, according to this theory, is particularly powerful at ley line intersections.
In the U.S., the most famous ley line map is of Seattle. The Geo Group produced the map with a $5,000 grant from the Seattle Arts Commission.