 They serve to link the opposing sides of the narrow valley passes and are now most used for hiking excursions.In times past these structures were rather rare and functioned as important transportation routes connecting Rome and the surrounding region of Lazio with Abruzzo and the Adriatic Sea.One of the most famous is called the "Tracciolino di Annibale", taking its name from the legend that Hannibal once traveled over this route on his way from Carthage to Rome.