Which one of the following innovations enabled Romans to erect giant amphitheaters, public baths, and high-rise tenement buildings?

Question

Quizplus · Accepted Answer

Concrete was a versatile and durable building material that allowed Romans to construct impressive structures such as the Colosseum, the Baths of Caracalla, and multi-story apartment buildings (insulae). Steel was not widely used until much later and calculus was not developed until the Middle Ages.

Which One of the Following Innovations Enabled Romans to Erect