*Imperial Rome.* Roman society under the Principate exhibits in general the same characteristics as during the last century of the Republic. Rome itself was a thoroughly cosmopolitan city, where the concentration of wealth and political power attracted the ambitious, the adventurous and the curious from all lands. Whole quarters were occupied by various nationalities, most prominent among whom were the Greeks, the Syrians, and the Jews, speaking their own languages and plying their native trades. With the freeborn foreign population mingled the thousands of slaves and freedmen of every race and tongue. During the first and second century the population of Rome must have been in the neighborhood of one million, but in the third century it began to decline as a result of pestilence and the general bankruptcy of the empire. Inevitably in such a city there were the sharpest contrasts between riches and poverty, and the luxurious palaces of the wealthy were matched by the squalid tenements of the proletariat. In outward appearance Rome underwent a transformation which made her worthy to be capital of so vast an empire. This was largely due to the great number of public buildings erected by the various emperors and to the lavish employment of marble in public and private architecture from the time of Augustus. The temples, basilicas, fora, aqueducts, public baths, theatres, palaces, triumphal arches, statues, and parks combined to arouse the enthusiastic admiration of travelers and the pride of its inhabitants. But, although after the great fire of 64 A. D. many improvements were made in the plan of the city, restrictions placed upon the height of buildings, and fireproof construction required for the lower stories, still the streets remained narrow and dingy, the lofty tenements were of flimsy construction, in perpetual danger of collapse, and devastating conflagrations occurred periodically.