Their huge system of stone roads. They used relay teams to carry messages as far as 150 miles a day. Their most remarkable example of stonework is Machu Piccu.
Achievements of the Aztec
The Aztec centered on warfare. They believed that it was a religious duty to serve in the war and that and that anyone who died in battle was honoring their god of war. (Huitzilopochtli)
Acheivements of the Maya
They were among the first civilizations to understand the mathematical concept of zero, they developed a 365 day calendar, they created hieroglyphs and also used the cut and burn method with their crops.