Topic: Tell me a short, interesting fact about

One interesting fact about the Roman Empire is that it was the first civilization to use concrete for large-scale construction. The Roman concrete, known as "opus caementicium," was a mix of volcanic ash (pozzolana), lime, and seawater, which when combined produced a durable, water-resistant material. This allowed the Romans to build structures such as the Colosseum, the Pantheon, and many aqueducts that are still standing today, over 2000 years after their construction.