The Devil’s Playground Loop is located in a remote corner of Petrified Forest National Park, in northeast Arizona. This part of the park has hoodoos and other magical rock formations. They have been formed mainly by erosion and are highlighted by bands of blue, purple, and gray. The 2 page park pamphlet for this loop (which doesn’t appear to be online) says that it starts just past the Lithodendron Wash, next to the 2 brown NPS signs (pictured below). The gpx file should be taken as a general guide.

This route will take you from the North of London to the South...and then back up again, hitting every single station along the way. 

Having lived in London all my life, I’d look at the rail maps and wondered if it was possible to run whole lines in one go and so started my interest in exploring different parts of London whilst running’s the train lines.