By the first century B.C., Rome was already the largest, richest, and most powerful city in the Mediterranean world. During the reign of Augustus, however, it was transformed into a truly imperial city. Writers were encouraged to compose works that proclaimed its imperial destiny: the Histories of Livy, no less than the Aeneid of Virgil, were intended to demonstrate that the gods had ordained Rome “mistress of the world.” A social and cultural program enlisting literature and the other arts revived time-honored values and customs, and promoted allegiance to Augustus and his family. The emperor was recognized as chief state priest, and many statues depicted him in the act of prayer or sacrifice. Sculpted monuments, such as the Ara Pacis Augustae built between 14 and 9 B.C., testify to the high artistic achievements of imperial sculptors under Augustus and a keen awareness of the potency of political symbolism. Religious cults were revived, temples rebuilt, and a number of public ceremonies and customs reinstated. Craftsmen from all around the Mediterranean established workshops that were soon producing a range of objects—silverware, gems, glass—of the highest quality and originality. Great advances were made in architecture and civil engineering through the innovative use of space and materials. By 1 A.D., Rome was transformed from a city of modest brick and local stone into a metropolis of marble with an improved water and food supply system, more public amenities such as baths, and other public buildings and monuments worthy of an imperial capital.