The inscriptions on the Porta Maggiore record the distances from the sources of the aqueducts to this point, clearly shewing that this was the entrance into Rome in the outer wall, though not into the CITY, until the boundary of the city was extended to this outer wall by Aurelian, in the third century. On the northern side of this great gate remains of the Marcian arcade were found going from this point, where the three aqueducts pass through the outer wall at one of the angles, and go straight on to the high bank on which the wall of Aurelian was afterwards carried, to the Porta Tiburtina (now di S. Lorenzo), and the reservoirs there. The _specus_ passes underground for some distance, about half-way between the two gates, and is carried on arches near the gates. The fine building called Minerva Medica was full of fountains, as was all the great public garden in which it stands, and all the fountains in Rome were supplied by the aqueducts. Between this building, of the third century, and the wall, is another large reservoir, turned into a house, where considerable excavations have been made. The later aqueduct, called Aqua Alexandrina, was carried in the wall over the earlier ones, to a point just opposite, to the remains of the Minerva Medica. The piers of the arches that supported the _specus_ can be seen in the wall, both outside and inside, as far as this, but they go no farther. This point, where they cease, is close to the place where the railway passes through the wall. Beyond these arches other excavations were made by the archæologists near the Porta di S. Lorenzo, and the arches that carried the Marcia, etc., were shewn. There are remains of two reservoirs near this point; the outer wall of one now forms part of the city wall, and is foolishly called “the house of Cicero;” the other is just within the line, but still on the bank, with the wall of Aurelian built close against it on the outer side. There are remains of another reservoir on the other side of the gate, and one branch goes on from thence to the Prætorian Camp, passing by the Porta Chiusa, where the _specus_ was shewn in some other excavations of the archæologists; and near to it, on the south side, is a large reservoir on the bank, cut through the middle by the wall of Aurelian. This proves that the great bank of earth was there, and had the aqueducts carried upon it, before the time that the wall of Aurelian was built. The _specus_ then goes upon the bank round this camp, but is for the most part concealed; it is visible again on the northern side, which is the only perfect part of the fortification of the camp by Tiberius, and his wall stands upon the earlier _specus_ of the aqueduct; the latter is faced with _opus reticulatum_ where perfect; the wall is of fine brickwork.