It will be necessary to speak further of the cyclopean wall on the east side of the city from the Porta del Sole to the Portella, for it has always been supposed that this part of the wall was exactly like the rest, and dated from the same period. But a careful examination shows that the stones in this lower portion are laid more regularly than those in the wall above the Portella, that they are more flatly faced on the outside, and that here and there a little mortar is used. Above all, however, there is in the wall on one of the stones under the house no. 24, Via della Fontana an inscription,[40] which Richter, Dressel, and Dessau all think was there when the stone was put in the wall, and incline to allow no very remote date for the building of the wall at that point. To me, after a comparative study of this wall and the one at Norba, the two seem to date from very nearly the same time, and no one now dares attribute great antiquity to the walls of Norba. But the rest of the cyclopean wall of Praeneste is very ancient, certainly a century, perhaps two or three centuries, older than the part from the Portella down. There remains still to be discussed the lower wall of the city on the south, and a restraining terrace wall along part of the present Corso Pierluigi. The stretch of city wall from the Porta del Sole clear across the south front to the Porta di S. Martino is of opus quadratum, with the exception of a stretch of opus incertum[41] below and east of the Barberini gardens, and a small space where the city sewage has destroyed all vestige of a wall. The restraining wall just mentioned is also of opus quadratum and is to be found along the south side of the Corso, but can be seen only from the winecellars on the terrace below that street. These walls of opus quadratum were built with a purpose, to be sure, but their entire meaning has not been understood.[42] The upper wall, the one along the Corso, can not be traced farther than the Piazza Garibaldi, in front of the Cathedral. It has been a mistake to consider this a high wall. It was built simply to level up with the Corso terrace, partly to give more space on the terrace, partly to make room for a road which ran across the city here between two gates no longer in existence. But more especially was it built to be the lower support for a gigantic water reservoir which extends under nearly the whole width of this terrace from about Corso Pierluigi No. 88 almost to the Cathedral.[43] The four sides of this great reservoir are also of opus quadratum laid header and stretcher.