A few years ago I trekked along part of the Camino Inca - a 45 km track at high altitude through the Andean mountains finishing at the amazing ancient Incan site of Machu Picchu in Peru. About 5 km into the trek we arrived at one of the extraordinary sacred sites along the way to have a short break. As we stood there taking in the view our tour guide shared that down below along the river was a track that merchants used to take to get to Machu Picchu that only took about 6 ho