What was Roman architecture structures made out of?

Roman architecture primarily utilized materials such as concrete, brick, and stone, particularly limestone and marble. Concrete, a revolutionary innovation of the Romans, allowed for the construction of larger and more durable structures. Additionally, they often used travertine and volcanic tuff for various buildings, while decorative elements frequently incorporated marble. This combination of materials enabled the Romans to create impressive structures like aqueducts, amphitheaters, and temples that have withstood the test of time.