ROMAN ARCHITECTURE. 139 the exterior seems to have been of small pretensions, in com- parison with the interior. Trajan's (the Ulpian) Basilica, Rome (a.d. 98) (Nos. 47=, 58 B, e), of which Apollodorus of Damascus was the architect, was a fine example of the wooden roofed type. Entered from Trajan's Forum, it had a central nave 87 feet wide with double aisles, each -23 feet g inches wide, and an internal length excluding the apses of 385 feet. The total internal height was about 120 feet. The columns on the ground story separating the nave and aisles were of red granite from Syene, with white marble Corinthian capitals. At each end were semicircular apses, readied by flights of steps, having sacrificial altars in front of them. Galleries were formed over the side aisles, reached by steps as shown on the plan. Adjoining the Basilica were the Greek and Latin libraries, and Trajan's famous Column (page 156) stood in an open court between them. The Basilica of Maxentius or Constantine, Rome (a.d. 312) (Nos. 46 I, 47'", 58 A, c, d), formerly erroneously known as the Temple of Peace, consists of a central nave 265 feet long by 83 feet wide between the piers, crowned at a height of 120 feet by an immense groined vault in three compartments. To the north and south are aisles roofed with three great semi- circular vaults, each 76 feet in span, springing from walls placed at right angles to the nave. These walls had communicating openings formed in them, and aided by the weight of the aisle vaults, supported that of the nave. Monolithic columns were attached to the face of these piers, and supported pieces of entablature from which sprung the groined vaults. There were two apses, one to the north and one to the west of the central nave. Light was introduced in the upper part of the nave over the aisle vaults by means of lunettes, or semicircular windows in the wall formed by the intersecting vaulting. The building is similar as regards plan and design to the Tepidarium of the Thermae (No. 59), and is in many respects a prototype of a Gothic struc- ture, in which the thrust and weight of an intersecting vault are collected and brought down on piers built to receive them. The vaults to the northern aisle still remain, exhibiting the deep coffering executed in brick work, and a portion of the main vault of concrete formed of pozzolana is still in position, although the column which was placed to carry it has been removed, thus showing the extraordinary tenacity of Roman concrete. Other basilicas at Rome were the Basilica Porcia (b.c. 184), believed to be the oldest, the Basilica Julia (No. 47), and the Basilica Amelia (No, 47) ; and the basilicas at Pompeii, Farno, and Treves, and at Silchester in England, may be mentioned.
