The New World is rarely considered for its broad-scale architectural endeavours, but the Inca, a militant culture which rose to hegemony of western South America from 1200-1535 AD, devised one of the most sophisticated ancient road systems since the time of the Romans. Spanning the 25,000 km from the Inca capital of Cuzco (in the southern Andes Mountains), it is even more impressive by virtue of the terrain it crossed; riven with snow, swamp, jungle, rivers, mountains, valleys and very little level ground, it took the breath from the Spanish explorers who rediscovered it. Pedro de Cieza de León invoked images of old world triumphs, then dismissed them in wishing that “Alexander, or any of the ancient kings who ruled the world... built such a road.”
Two roads were the primary arteries of travel. The Qhapaq Nan (or ‘opulent way’) ran through the highland between Cuzco and Quito (near the Columbian border of modern Ecuador) and a parallel road ran along the coast. Littered throughout were small capillary roads, which led as far north as Chile and as far east as north-western Argentina. Many roads served military and trade functions, serving to link a nation of six million subjects, although others led to high (5000 metres) mountain-top sanctuaries used for religious ceremonial purposes.
The roads themselves were remarkable to the explorers; in many cases, preconceptions of inherent cultural superiority were dashed when they encountered such sophisticated features as stone paving (not found along the coast), culverts, drainage canals (which were used for irrigation purposes in a manner similar to Roman aqueducts) and elevated causeways. As South American peoples had made no motive use of the wheel, steps or zig-zags were used to counter steep slopes. The roads often ran adjacent to stone quarries, enabling further construction or repairs. In highland areas, roads were often simply cut directly into the rock, wrapping around mountain peaks. The width of the roads varied between 16 metres (in areas where the mobilisation of large forces or prolific commerce occurred) and a mere 1 metre along the high mountain paths which saw little use.
Many bridges were necessary (to ford rivers or precipitous drops), although the Incas never invented the arch. As a result, they devised and primarily used braided rope suspension bridges which sagged in the middle, although the Inca also made less grandiose wood and stone bridges to cross small gaps. Despite their ingeniously simple construction, it took an organised task force several weeks to rebuild a damaged bridge, even under professional supervision. A few of these traditional bridges still exist in areas around the ancient Inca capital; the most famous suspension bridge, spanning the Apurimac Gorge (45 metres), was maintained well into the 19th century.
Sources:
Books:
Archaeology: the Definitive Guide, various authors.
Internet:
www.le.ac.uk/archaeology/rug/AR210/IncaProject/IncaRoads.html
http://www.spanish.sbc.edu/MMLatAm/Mapofroads.html