We learn from Suetonius and Tacitus that it was situated on the western side of the Palatine, overlooking and communicating with the Velabrum. The remains consist of vast halls and substructions, and a row of arches supposed to have been the guard's quarters. This palace has yet to be excavated. THE PALACE OF CALIGULA AND HADRIAN (2). "Having continued part of the Palatine as far as the Forum, he converted the Temple of Castor and Pollux into the vestibule of his house." "He built a bridge over the temple of the deified Augustus, by which he joined the Palatine to the Capitol" (Suetonius). He connected his palace with that of Tiberius by means of porticoes. The remains consist of a suite of rooms, portions built over the Clivus Victoriæ, chambers with fresco and stucco decorations, and mosaic pavements, also a portion of the beautiful marble balustrade of the solarium. Suetonius tells us that this palace was destroyed by fire; in fact, most of the remains show the construction of Hadrian, who must have rebuilt it and used it as his palace. The remains of this palace have been recently uncovered at the northern side of the Palatine. It appears that the palace was built in a series of terraces against the Palatine Hill, the construction showing work of Caligula, Trajan, and Septimius Severus. There are some chambers which were warmed with hot air in terra-cotta pipes, and containing fragments of statuary on the lowest level excavated. Then, on the terrace above, there is an arcade paved with blocks of silex, and on one side shops. A flight of travertine steps conducts to some small chambers above, with mosaic pavements and frescoes, which were built by Hadrian against a wall of Caligula having frescoes on yellow and white grounds. The side walls and vaults are decorated with frescoes of the time of Hadrian. [Illustration: PLAN OF THE PALACE OF DOMITIAN, A.D. 81-96. A, Tablinium. B, Lararium. C, Basilica. D, Vestibule. E, Tricliniarium. F, Nymphæum. G, Temple Jupiter Victor. H, Vometarium. K, Cubiculum.] [Illustration: PLAN OF HOUSE OF GERMANICUS, A.D. 1] THE PALACE OF DOMITIAN (17). He used the remains of Augustus's palace, destroyed by fire in the second year of the reign of Titus, filling in the chambers of the earlier buildings with earth, so that they formed a solid foundation. "He embellished the portico, in which he took his airing, with polished stone, so that he might observe if any one approached him" (Suetonius). The remains consist of the tablinium, or summer-parlour; the lararium, or chapel of the household gods; the bed-chamber where he was assassinated; the tricliniarium, or dining-room; the peristylium, or open court; nymphæum, or aquarium; the vometarium; auditorium; and the crypto-porticoes connecting it with the other palaces. THE BASILICA (16).