Among the many roads and trails constructed in pre-Columbian South America, the Inca road system, or Qhapaq Ñan was the most extensive. The network was based on two north-south roads. The eastern route ran high in the puna and mountain valleys from Quito, Ecuador to Mendoza, Argentina. The western route followed the coastal plain except in coastal deserts where it hugged the foothills. More than twenty routes ran over the western mountains, while others traversed the eastern cordilla in the montana and lowlands. Some of these roads reach heights of over 5,000 metres (16,000 ft) above sea level.The trails connected the regions of the Inca empire from the northern provincial capital in Quito, Ecuador past the modern city of Santiago, Chile in the south. The Inca road system linked together about 40,000 km of roadway and provided access to over three million km² of territory.

The roads provided routes for rapid communication, personnel movement, and logistical support. The prime users were soldiers, porters and llama caravans, along with the nobility and individuals on official duty. Permission was required before others could walk along the roads, and tolls were charged at some bridges. Although the Inca roads varied greatly in scale, construction and appearance, for the most part they varied between about one and four meters in width.

Much of the system was the result of the Incas claiming exclusive right over numerous traditional routes, some of which had been built centuries earlier. Many new sections were built or upgraded substantially: through Chile's Atacama desert, and along the western margin of Lake Titicaca, as two examples.

Spanish chroniclers frequently described lengthy journeys made by the Inca ruler, carried on a litter, and surrounded by thousands of soldiers and retainers, to various parts of his empire.

Because the Incas did not make use of the wheel for transportation, and did not have horses until the arrival of the Spanish in Peru in the 16th century, the trails were used almost exclusively by people walking, sometimes accompanied by pack animals, usually the llama.

Relay messengers, or chasqui, stationed at intervals of 6 to 9 km, carried both messages and objects such as fresh marine fish for the rulers in the sierra. Messages consisted of knotted-cord records known as quipu along with a spoken message. Chaskis could cover an estimated 240 km per day.

There were at least 1,000 and perhaps 2,000 way stations or tambos, placed at even intervals along the trails. These structures were intended to lodge and provision itinerant state personnel.

Various means were used to bridge water courses. Rafts were used to cross wide meandering rivers. Bridges built of stone or floating reeds were used in marshy highlands. Inca rope bridges provided access across narrow valleys. A bridge across the Apurimac River, west of Cusco, spanned a distance of 45 meters. Ravines were sometimes crossed by hanging baskets, or oroya, which could span distances of over 50 meters. Bridges were sometimes built in pairs.

INCA TRAIL CLASSIC:
Trekkers normally take three or four days to complete the "Classic Inca Trail".
It starts from one of two points: km 88 or km 82 from Cusco on the Urubamba River at approximately 2,800 m altitude.
Patallacta viewed from above. Both of these trail segments meet above the Inca ruins of Patallacta (aka Llaqtapata), a site used for religious and ceremonial functions, crop production, and housing for soldiers from the nearby hilltop site of Willkaraqay, an ancient pre-Inca site first inhabited around 500 BC. The trail undulates, but overall ascends along Rio Cusichca (aka River Kusichca aka "happy river").

At the small village of Wayllabamba the trail intersects with the "Mollepata Trail" at 3,000 metres (9,800 ft).

Small, permanent settlements are located adjacent to the trail, and Wayllabamba has approximately 400 inhabitants (130 families) spread along this portion of the trail, and pack animals—horses, mules, donkeys, and llamas—are allowed.

At Wayllabamba the trail to Machu Picchu turns west and begins ascending along a tributary of the Cusichca. Because of previous damage caused by hooves, pack animals are not allowed on the remainder of the trail. For the same reason, metal-tipped trekking poles are not allowed on the trail.

Inca Trail cloud forest.As the trail ascends toward, Warmiwañusca or "Dead Woman's Pass", which resembles a supine woman, it passes through differing habitats, one of which is a cloud forest containing Polylepis trees. The campsite at Llulluchapampa is located on this stretch of trail at 3,800 metres (12,000 ft). The pass itself is located at 4,215 m above sea level, and is the highest point on this, the "Classic" trail. After crossing the pass the trail drops steeply into the Pacaymayu River drainage. At a distance of 2.1 km and 600 m below the pass is the campground Pacaymayu.

The tambo Runkuraqay.After passing Pacaymayu the trail begins steeply ascending the other side of the valley. One kilometer along the trail, at an altitude of 3750m is the Incan tambo of Runkuraqay, which overlooks the valley. The site was heavily restored in the late 1990s.

The trail continues to ascend, passing a small lake named Laguna Cochapata[16] in an area that is recognized as deer habitat. This site had been used as a camp site. As with other sites that were being degraded due to overuse, camping is no longer allowed. The trail reaches the pass at an altitude of 3,950 m.

Once again the trail descends steeply, then more gently, passes another small lake and soon affords a view of Sayaqmarka, perched atop a sheer rocky spur. Sayaqmarka is at an altitude of 3,600 metres (12,000 ft). A steep, narrow staircase leads up to the extensive, heavily restored ruins, which include many buildings spread along approximately 80 m of ridge top. This site was named by a 1940s expedition by Paul Fejos and Sayaqmarka can be translated as "inaccesible town". Sayaqmarka overlooks both the "Classic Inca Trail" and another uncleared trail that leads down into the Aobamba River drainage, and was a signaling location. There are no argicultrual terraces here, but the nearby site of Conchamarka (Shell Town), a small group of Incan buildings standing on rounded terraces, is clearly visible. After descending into a small drainage and Conchamarke, the trail begins an accent and within 0.6 km passes a campground at Chaquicocha.

The Trail continues through high cloud forest, undulating, sometimes steeply while affording increasingly dramatic viewpoints of mountains and dropoffs. A long Inca tunnel and a viewpoint overlooking two valleys: the Urubamba and Aobamba, are passed.

Ruinas Phuyupatamarka.Another high point at altitude of 3,650 m is crossed, followed by a campground, and then after a short descent, a site with extensive ruins. The name Phuyupatmarka (Cloud-level Town)(poo-yoo-patta-marka) is applied to both the campground, and the ruins. Howard Bingham discovered the site, but left most of it covered with vegetation. The Fejos team named the site, and uncovered the remainder. Design of the site closely follows the natural contours, and includes five fountains and an altar, which was probably used for llama sacrifice.

The trail then descends approximately 1,000 meters including an irregular staircase of from 1,300 to 1,500 steps, some of which were carved into solid granite. Vegetation becomes more dense, lush, and "jungle" like with an accompanying increase in butterfiles and birds. A second Incan tunnel is along this section of trail.

Intipata.Even before passing through the tunnel there are views down to the Urubamba River, the first since leaving the river at Patallacta. The number of these views increases. After the tunnel the town of Aguas Calientes can be seen, and trains running along the river can be heard. As the trail nears Intipata, it affords views of the "Two Day" Inca Trail (aka "Camino Real de los Inkas" or "One Day Inca Trail"). A small spur of the trail leads directly to Wiñay Wayna, while the main route continues to Intipata.

Intipata (sunny place aka Yunkapata) is a recently uncovered extensive set of argicultural terraces which follow the convex shape of the terrain. Potatoes, maize, fruit, and sweet potato were grown here.

Winaywayna, showing upper and lower structuresThe name Wiñay Wayna (forever young) (win-yay-way-na) is used to refer to both a hostel–restaurant–camp site and a set of Inca ruins. Two groups of major architectural structures, a lower and upper, are set among multiple agricultural terraces at this concave mountainside site. A long flight of fountains or ritual baths utilizing as many as 19 springs runs between the two groups of buildings.

From Wiñay Wayna the trail undulates along below the crest of the east slope of the mountain named Machu Picchu. The steep stairs leading to Intipunku (sun gate) are reached after approximately 3 km. Reaching the crest of this ridge reveals the grandeur of the ruins of Machu Picchu, which lie below. A short downhill walk is the final section of the trail.

INCA TRAIL TO MACHU PICCHU TOURS