THE CLOACA MAXIMA,
originally made by Tarquinius Superbus in the year 138 of Rome, or 530 years before Christ: part of the actual construction appears to be original and of that time. It is built of the larger blocks of tufa, and has a round-headed vault. The German theory is, that this great drain was originally open at the top, and not vaulted over till the time of Camillus, after the capture of Veii in the war with the Etruscans; but the construction does not agree with this. The additional branch of the Cloaca made by Agrippa to carry off the water from his thermæ near the Pantheon (to supply which the Aqua Virgo was made), is of brick, after the fashion of his time. This can be seen at the junction near the Church of S. Giorgio in Velabro or the Janus Quadrifrons. Several natural streams of water are collected in this great drain, and still run through it. One, from the Quirinal, runs straight between the Palatine and the Capitol; a second comes from the eastern side of the Palatine and the Arch of Titus; a third runs from the Capitol, the spring being in the lower chamber of the Prison of S. Peter. All these met near the Forum Romanum, and formed the Lake of Curtius, which was drained by the great Cloaca. But this drain is not so low down as the lake is deep; consequently there is always a swamp there, even now, after much rain. Two other streams fall into it near the Janus,—one from the direction of the Pantheon; the other from the western side of the Palatine, coming out of the cave called the Lupercal, where the water gushes out from under the arch with great force. This is called the Aqua Argentina, or the Silvery Water, either from its beautiful clearness, or because it went through the silversmiths' quarter.
Regaining the Via S. Teodoro, turn left, under the Palatine. On the right is the