Rome had many advances in engineering that helped make them such a successful civilization. They invented the aqueduct, which allowed the Romans to have running water and an extensive sewer system. The Romans were a very clean people, which reduced the spread of illness and disease. Also, the Romans engineered a waterproof concrete by using a volcanic sand called pozzolan. Not only was this concrete much stronger, it enabled the Romans to build underwater. Lastly, the Romans engineered the coliseum, a huge arena that holds 50,000+ people and still stands today.