Hidden in the deserts of the #West is the location of #NorthAmerica's most significant #Railroad achievement. Watch new episodes of #ImpossibleEngineering Wednesdays at 9p ET on Science Channel and on SCIgo. | Science Channel

Five Impossible Tenochtitlan Engineering Marvels Long before Europe mastered large-scale urban planning, Tenochtitlan stood as one of the most advanced cities on Earth. Built on a lake, this Aztec capital solved problems that modern engineers still struggle with — fresh water, transportation, food production, and flood control — all without metal tools or draft animals. Its “impossible” engineering marvels included floating farms that fed hundreds of thousands, massive stone causeways that could