There are two routes connecting Amman with the south of Jordan: the Desert Highway and the King's Highway. If your time is limited, use the straighter and faster Desert Highway. However, by far the more interesting route is the King's Highway, which twists and winds its way through the heart of Jordan, connecting Madaba, Karak, Tafileh, Shobak and Petra. The King's Highway is the world's oldest continuously used communication route, and is mentioned early in the Bible. In Numbers 20, Moses requests the king of Edom to allow his people to "travel along the king's highway and not turn to the right or to the left until we have passed through your territory.
Jordan Tourism