The influx of barbarians, a corrupted government, poor defenses, a decaying city, overpopulation… Historians have suggested many forces that led to the fall of the Roman Empire, but today, let’s start with a part of the empire that didn’t fall (and still hasn’t). Ancient Romans made what is considered the world’s strongest concrete. “The harbor concrete, a mixture of volcanic ash and quicklime, has withstood the sea for two millennia and counting. What’s more, it is stronger than when it was first mixed.” Concrete that can not only withstand seawater, but that actually becomes stronger as it soaks in it, sounds like a product that could be pretty useful in the relatively near future. From WaPo: Ancient Romans made world’s ‘most durable’ concrete. We might use it to stop rising seas.