The first great achievement of the Roman Empire, Pax Romana, was notable for what did not occur. From approximately 27 BC to AD 180—the reign of Augustus through that of Marcus Aurelius—the Roman Empire enjoyed relative peace, the longest such period in Western history before or since. During this period Rome prospered economically and culturally and witnessed the construction of several prominent buildings, such as the Colosseum, which was built between 70 and 82.