On the other hand, in the interior of the =Basilica Ulpia= a range of columns, supporting an entablature, took the place of the piers on each side of the nave. On the entablature rested another range of columns, surmounted by another entablature, above which walls, pierced with windows, were carried up to carry the flat, coffered ceiling. Both tiers of nave columns opened into the aisle, which correspondingly had two stories, the upper crowned with a flat ceiling. =Arches, Columns of Victory.=--The magnificence of Rome and other cities was further displayed in the Triumphal Arches and Columns of Victory erected in honour of emperors and conquerors. The arch was of two types: the single arch and the three-arched. A famous example of the former is the =Arch of Titus=, which commemorated the capture of Jerusalem, <small>A.D.</small> 70. Examples of the three-arched type are those of =Septimus Severus=, and of =Constantine= in =Rome=, and the =Arch at Orange=. The façades were adorned with columns of the Corinthian or Composite orders, partially or wholly detached, supporting a _broken_ entablature--one, in which the uniformity of projection is interrupted by a projection over each capital. Above it is a top-story, known as the _attic_. The soffit of the arch was richly coffered and the wall spaces embellished with low-reliefs, representing incidents of triumph, while the attic bore upon its face an inscription and was surmounted by statues or a four-horse triumphal chariot (_quadriga_). The most famous of all the pillars of victory is =Trajan’s Column=, erected in connection with his Basilica. It is a column of the Roman Doric order, mounted upon a lofty pedestal, the height over all being 147 feet. The shaft, 12 feet in diameter at the base, encloses a spiral staircase of marble, while its exterior is decorated with a spiral band, 800 feet long and 3½ feet wide, carved with reliefs, representing incidents in Trajan’s victorious campaigns against the Dacians. It stood originally in a court of the =Basilica Ulpia=, from the several galleries of which the sculpture could be viewed. The statue of Trajan which originally adorned the summit of the pillar has been replaced by a bronze statue of St. Peter. A special pillar of imperial times was the Rostral Column, erected in commemoration of a naval victory and decorated with the bronze beaks or prows taken from the enemy’s ships. =Palaces.=--Augustus set the example of building himself a palace, choosing the Palatine Hill, to which successive emperors, particularly Tiberius, Caligula, Nero, Domitian, and Septimus Severus, made additions of increasing splendour. Nothing remains but ruins, which, however, show that the principal apartments were as follows: the Tablinum or throne-room; Basilica, or hall of justice; Peristylium or rectangular garden-court, enclosed with colonnades; Triclinium, or Banquet Hall; Lararium or domestic temple for the household gods and the Nymphæum.