The Inca empire of South America was connected by a network of roads used by chasqui runners and pack llamas carrying messages and supplies around the empire. The Inca, creating their empire in the Andes mountains, faced challenges unlike those of flat-land and river-valley empires, among which was the problem of crossing numerous steep mountain valleys and rivers that ran dangerously swift in the flood season. Their solution to this problem was: rope bridges.
Suspension rope bridges spanned rivers and valleys, the longest reaching a length of 45 meters. They were made with ropes twisted out of grass and had to be rebuilt every year or two. The rebuilding was dangerous work that was assigned to local villagers as part of their obligation to the empire. Most Inca bridges have long since been replaced with modern structures, but one, the Q’iswa Chaka over the Apurimac River in Peru, is still rebuilt every year by local people as a way of preserving their heritage.