Of all the palaces which the Roman emperors built for themselves, and which we know from historical records to have been of the most magnificent description, nothing now remains in Rome itself that is not too completely ruined to enable any one to restore its plan with accuracy, though considerable remains exist of the Palace of the Cæsars on the Palatine Hill. In fact, the palace of Diocletian at Spalatro, in Dalmatia, is the only remaining example in the whole of the Roman empire of the dwelling-house of an emperor, and even this was not built till after Diocletian had resigned the imperial dignity, so that its date is the early part of the fourth century A.D. This palace is a rectangle, measuring about 700 ft. one way and 590 ft. the other, and covers an area of nearly 10 acres. It is surrounded by high walls, broken at intervals by square and octagonal towers, and contains temples, baths, and extensive galleries, besides the private apartments of the Emperor and dwellings for the principal officers of the household. The architect of this building broke away from classical traditions to a great extent; for example, the columns stand on corbels instead of pedestals, the entablatures being much broken, and the arches spring directly from the capitals of the columns (Fig. 149). The private houses in Borne were of two kinds: the _insula_ and the _domus_. The insula was a block of buildings several stories high, frequently let out to different families in flats. The ground-floor was generally given up to shops, which had no connection with the upper parts of the building; and one roof covered the whole. This kind of house was generally tenanted by the poorer class of tradesmen and artificers. The other kind of house, the domus, was a detached mansion. The excavations at Pompeii have done much to elucidate a number of points in connection with Roman dwellings which had been the subject of much discussion by scholars, but we must not too hastily assume that the Pompeian houses are the exact counterpart of those of ancient Rome, as Pompeii was what may be called a Romano-Greek city. [Illustration: FIG. 140.--GROUND-PLAN OF THE HOUSE OF PANSA, POMPEII.] [Illustration: FIG. 141.--GROUND-PLAN OF THE HOUSE OF THE TRAGIC POET, POMPEII.]