The Incas, of course, didn't invent the road -- that honor would no doubt go to the Romans -- but they did invent a network of roads and highways that connected their territory on a scale never seen before in South America.
At its peak, the Incan highway system covered nearly 25,000 miles (40,000 kilometers) with roads that ranged from 3 to 13 feet (1 to 4 meters) in width and consisted of everything from simple dirt paths to passageways covered in fine paving stones [source: McEwan]. The network had main thoroughfares known as the imperial highway system, or Capac-Nan. These roads ran on a more or less north-south trajectory, with one hugging the coastline and another running roughly parallel through the mountains. Smaller roads connected the two main arteries with all of the provincial centers of the empire. The entire system was reserved for government officials; if you were a commoner, you needed to seek special permission to walk the Capac-Nan.
Official business parties could travel approximately 20 miles (32 kilometers) per day along the Capac-Nan [source: McEwan]. Resting stations known as tampus were located along the roadways at approximately the same distance to offer travelers food, lodging and a chance to resupply. Rest was critical for these groups -- especially for the men whose shoulders carried nobles on raised platforms known as litters.