Augustus introduced numerous social reforms, especially those calculated to restore the ancient morality of the Roman people and the integrity of marriage; he attempted to combat the licentiousness of the times and sought to restore the ancient religious festivals. He adorned the city with temples, basilicas, and porticoes, transforming it from a city of brick to a city of marble. To the Romans an era of peace and prosperity seemed to have dawned, and the Augustan period represents the culmination of the Golden Age of Latin literature, distinguished in poetry by the achievements of Virgil, Horace, and Ovid, and in prose by Livy's monumental History of Rome.
With the establishment of the imperial system the history of Rome became largely identified with the reigns of individual emperors. The emperor Tiberius, who succeeded his stepfather Augustus in AD 14 and ruled until the year 37, was a capable administrator but the object of general dislike and suspicion. He relied on military power and in Rome had his Praetorian Guard, the only organized troops allowed legally in Rome, within ready call. He was followed by the insane and tyrannical Caligula, who reigned from 37 to 41; Claudius, whose rule (41-54) was distinguished by the conquest of Britain, and who continued the public works and administrative reforms instituted under Caesar and Augustus; and Nero, whose rule was at first moderate, as a result of the wise guidance and counsel of the philosopher Lucius Annaeus Seneca and of Sextus Afranius Burrus (died 62), prefect of the Praetorian Guard. Nero's overthrow, which was caused by his later excesses, and his subsequent suicide in 68 marked the end of the line of Julio-Claudian emperors.