I believe it was the Inan civilization. The Incans were/are not only known for their precise stone buildings. They also were the first to develop a mail system, water canal system for agriculture, and created their own written language. Throughout the Incan Empire, you will notice walkways extended all throughout western South America. Also, they built stairway-like steps down some parts of the Andes for rain water to travel down. This was an advantage for their crops.