And again: “Rivus Appiæ, sub Cœlio monte et Aventino actus, emergit, ut diximus, infra clivum Publicii.” (Ibid., c. 22.) The cave reservoir which formed the mouth of this stream, where it was distributed, has been found near the Marmorata, or marble-wharf. The Porta Trigemina was between that and the Salaria, or salt-wharf. Both of the wharves are still in use. Some good antiquaries consider that the Porta Trigemina consisted of three double gates, at intervals along the narrow strip of ground between the Aventine and the Tiber, and that the one of which remains have been found near the Sublician bridge was the middle one of the three: if so, this cave would be literally in the Porta Trigemina. In any case, it must have been close to it.
[11] That is, in the reservoir, or castellum aquæ, through which the conduit or specus passed. This reservoir exists, or rather considerable remains of it, just within the Porta Maggiore, between that and the church of S. Croce, and just outside the agger of the Sessorium, on which the road from S. Croce to this gate now runs.
[12] “... Cujus aquæ ad caput inveniri mensura non potuit, quoniam ex duobus rivis constat. Ad Gemellos tamen, qui locus est infra Spem (Specum) veterem, ubi jungitur cum ramo Augustæ, inveni altitudinem aquæ pedum quinque, latitudinem pedis unius, dodrantis: fiunt areæ pedes octo, dodrans: ... quas esse ex eo adparet quod in plerisque urbis partibus perdita aqua observatur, id est quæ ex ea manat, sed et quasdam fistulas intra urbem illicitas deprehendimus, extra urbem autem propter pressuram libræ, quam vidi infra terram ad caput pedibus quinquaginta, nullam accipit injuriam.” (Frontinus, c. 65.)
[13] There is good reason to believe that such tombs were not exclusively Etruscan, but were also used by the Latins and other nations at the same period, and this one may very well be early Roman.
[14] The modern carriage-road, so called, was called Via Gabina in the time of Frontinus. The old Via Prænestina is now a bridle-road only for the first three miles out of Rome, to the Torre de’ Scavi; it is then a cart-road, called Via Collatina, with a branch road into it from the present carriage-road.
[15] In the Map of Gell and Nibby, along the Via Prænestina will be seen the name Pupinia. The spot is just north of this, and not far off from the piece of road marked in the same map as the Via Collatina.
[16] Frontinus, c. 22.
[17] In the Bullettino dell’ Instituto Archeologico, and the Civiltà Cattolica, for the year 1861, it is stated that for the works of the iron railroad between the Via Labicana and the Via Gabina the specus of the Aqua Appia was found, 450 yards (metres) from the Porta Maggiore. It was constructed of square stone of tufa, and was incrusted with tartar, had an acute vault, which was 5 ft. 9 in. high, and 2½ ft. wide.
[18] This is on the line of the wall of Servius Tullius. It appears that Trajan made a reservoir here over the old one. The specus of the Appia passes through the present gardener’s house lengthwise, from east to west. This specus was found again in another excavation to the west of it, by the side of the present road.
[19] “Substitit ad veteres arcus madidamque Capenam.” (Juvenal, sat. iii. ver. 11.) “Capena grandi porta qua pluit gutta.” (Martial, lib. iii. epigr. 47.) The distance from the foot of the Cœlian to the Marrana is just a hundred yards along the line of the wall of Servius Tullius, across this part of the valley or great primitive foss. The ground on the side of the wall is all made earth and rubbish, and two aqueducts are carried on arcades against the wall, one on either side. These arcades have not been traced beyond the Marrana, the ground there being higher. At the Piscina Publica, where another pit was dug 20 ft. deep, the wall is built against the tufa rock, and there is a third specus in a tunnel in the rock under the wall.