Advanced Engineering Discovered at the Maya Observatory at Chichen Itza
In 1526, the Spanish conquistador Francisco de Montejo arrived on the Yucatan Peninsula of Mexico and found most of the great Maya cities deeply eroded and unoccupied. Many generations removed from the master builders, engineers, and scientists who conceived and built the cities, the remaining Maya they encountered had degenerated into waring groups who practiced blood rituals and human sacrifice.
Source: ancient-origins.net