Inca rope bridge
Gade, D.W., 1972, Bridge types in the central Andes:  Annals of the Association of American Geographers, v. 62 (1), p. 94-109.    [Shows the bridge at Huinchiri and predicts the art of building it will be lost within another generation;   fortunately, this prediction has proven untrue, and ethnic/adventure tourism may help save this bridge for posterity.]