The Qhapaq Ñan - bridges

Situated between 500 to 800 metres (1,600 to 2,600 ft) above sea level, this monumental road, which could reach 20 metres (66 ft) in width, connected populated areas, administrative centres, agricultural and mining zones as well as ceremonial centres and sacred spaces.

Various means were used to bridge water courses. There were multiple types of bridges used throughout the road system. Some bridges were made of simple logs, while others were built of stone or floating reeds were used in marshy highlands. Inca rope bridges also provided access across narrow valleys. Rafts were used to cross wide meandering rivers. A bridge across the Apurímac River, west of Cuzco, spanned a distance of 45 metres. Ravines were sometimes crossed by hanging baskets, or oroya, which could span distances of over 50 metres. Bridges were sometimes built in pairs.

https://www.youtube.com/watch?v=qptgIcQebLg

One of the difficulties of creating bridges was obtaining wood. Sometimes, the laborers who were making the bridges has to bring the lumber from very far away. In places where they had no timber, bridges would be built from ropes made of straw and grasses. If the bridges were made from rope, they had to be replaced about every two years, while if they were made from wood, they would not have to be replaced for about eight years.

The construction of these bridges was accomplished by the help of many workers. For simple log bridges, the construction was done by placing a series of logs over projecting canes. The construction of stone bridges was more complicated. The stone wall foundations for bridges were built with both rough and dressed stone. The masonry is extremely well fitted, with no evidence of any mortar being used to keep the stones in place.Rather, they used a method of stone working which used simple tools, such as hammerstones, to pound the rocks in a way that the contours of the upper rock matched those of the rock below so that the seams fit perfectly without mortar.