In 2014, UNESCO designated the Qhapaq Ñan, Andean Road System as being a World Heritage Site. The web site is full of resources including reports maps and great photos.
The Qhapaq Ñan, Andean Road System means Inca Empire network of roads operated by pedestrians with or without llamas:
Its is Interesting to see the objectives are the same as the Roman Empire Roads i.e. trade, communication,travel,defence,official mail, and security and a means of Building a Nation.
The network consists of nearly 20000 miles of almost 300 segments of roads with two big parallel roads concerning presently Bolivia,Perù,Chile,Colombia and Ecuador, with cross segments linked the two and a hub in Cuzco
One of these two corridors is approximately the one followed by the new Pan-American Highway
Thanks to Jean-Pierre Medeville for the suggestion.