Inca road system — Wikipedia

The Inca road system (also spelled Inka road system and in Quechua: Qhapaq Ñan meaning "royal road") was the most extensive and advanced transportation system in pre-Columbian South America. It was about 40,000 kilometres (25,000 mi) long in total. The construction of the roads required a large expenditure of time and effort. The network was composed of formal roads carefully planned, engineered, built, marked and maintained; paved where necessary, with stairways to gain elevation, bridges and accessory constructions such as retaining walls, and water drainage systems. It was based on two...