When we think of the Maya civilization, tall stone pyramids come to mind. But these ancient people were quite the engineers! Recently, scientists made a remarkable discovery in the city of Tikal in modern-day Guatemala. Here, they found evidence of an elaborate water filtering system within one of the city’s largest water reservoirs. They believe the filtering system may have been used to remove toxic metals like mercury, poisonous algae, and bacteria. Impressively, these materials are still used in modern-day water filtration, which just goes to show how technologically advanced the Maya…