Topic: Tell me a short, interesting fact about

One interesting fact about the Roman Empire is that it was the first known civilization to use concrete on a large scale. The Roman concrete, known as Opus caementicium, was a mixture of volcanic ash, lime, and pulverized bricks, pozzolana, which made it robust and long-lasting. This innovation led to the construction of famous Roman structures such as the Colosseum, Pantheon, and Aqueducts, which still stand today, more than 2000 years after they were built.