The original extent of the temple appears to have included only that part of the lower town, which lies between the modern streets of the Corso and the Borgo, and the ancient city principally lay on the side towards the citadel. But after Sylla had rebuilt the temple, its precincts reached as far downwards as the modern Contrada degli Arconi, and upwards to the Contrada Scacciato behind the baronial palace. The whole of this space was filled with a gradually ascending series of flights of marble stairs and terraces, arranged in a pyramidal form, at the summit of which stood the tholus or round temple of the goddess, 450 feet above the lowest terrace. The base of this pyramidal approach was 1275 feet broad, and the upper terraces gradually diminished in width. The temple faced the south, like those of Diana at Aricia, of Juno at Gabii and Lanuvium, and of Jupiter Capitolinus at Rome. The modes of construction found in the ruins are referred by Nibby to four different epochs--the polyhedral stonework of the primitive temple, which was incorporated in the buildings of the new; the squared stonework of the time of the Punic wars; the structures composed of smaller polygonal stones erected by Sylla; and the brickwork of the imperial times. There were five principal terraces or platforms rising one above the other. Nibby calls these the terrace of the cisterns, the terrace of the halls, the central terrace, the terrace of the recesses, and the terrace of the hemicycle. In front of the lowest terrace was a large open space on which the boundary of the sacred precincts was marked out by stone landmarks, some of which have been found on the spot. This open area was on the right of the Contrada degli Arconi, which takes its name from the arches still remaining. The sides of the area were bordered by two immense reservoirs. One of these is still entirely preserved, but the other is filled with rubbish. On the side of the open area towards the hill were twenty-nine arches, five of which in the centre projected, forming a kind of portico with fountains in niches, while the other twenty-four completed the sides towards the reservoirs. The style of these arches seems to indicate that they were built by Sylla as an addition to the older temple precincts. One arch on the left hand, and all the twelve on the right, still remain intact. They were probably used as rooms for the slaves belonging to the temple. [Sidenote: Reservoirs.]