At its height, the Maya civilization controlled roughly 125,000 square miles stretching across present-day Guatemala, Mexico, Honduras, and El Salvador, and this episode of the History Channel series traces how its engineers built cities like Tikal and Chichen Itza without metal tools, wheeled vehicles, or draft animals. Reenactments and location footage show step pyramids, ball courts, and astronomical observatories built to track Venus and the solar year, while historians and engineers explain the math and labor behind them. The film then follows the Aztecs, who inherited and expanded on Maya building methods to raise Tenochtitlan on a lake bed, using causeways, canals, and floating gardens called chinampas to support a capital of hundreds of thousands. Peter Weller narrates the arc from construction to collapse, tying architectural ambition to religious belief and political control, and closing with the Spanish conquest that ended both empires. The engineering detail, rather than the mythology, is the focus throughout.