The ancient aqueduct which was made use of for the purpose was the Julia (V.), (which see,) and the ancient arches mentioned probably mean the tunnel through which the water of the Aqua Crabra and the Marrana united is brought. Its course has been already described, the great reservoir or lake (_lacus_) opposite to the Porta Lateranensis is very distinctly visible in the vineyard by the side of the stream, between that and the Aurelian wall. It is still swampy ground, and is planted with canes; when these are cut at the end of the month of January, it can be clearly seen, and the remains of the lake intercept the path on the bank of the stream. This reservoir might be restored to use with great advantage to the neighbourhood, and at little expense. There are two mills on bridges across the stream on the side of this lake, and several other mills on the line of the stream, as has been mentioned. The water must always have flowed out of the lake in the old deep bed of the small river Almo, and passed under the bridge on which the Porta Metronia is built, into Regio I., and then under the foot of the Aventine by the side of the Circus Maximus into the Tiber, as before described. The tower built in the twelfth century, against the inside of the gate and the bridge, conceals this from view. XVIII. AQUA FELICE, A.D. 1587. This aqueduct is named after the Pope, Felice Peretti, whose title was Sixtus V.; he brought it from a place near La Colonna, the ancient Labicum, about twelve miles from the city, to the fountain of Moses (now so called from a statue) at the Termini on the Esquiline, as recorded on an inscription[199]. It is still in use, supplying the fountains at the Termini, near the Thermæ of Diocletian, of Monte Cavallo, near those of Constantine, and the whole of the upper town. The waters of the Aqua Hadriana were united with some others in the territory called Pantano, at about twelve miles from Rome, where they emerged from the mountains. All these sources or springs of water were collected during the pontificate of Gregory XIII., A.D. 1572-1585, in an immense reservoir, repaired in 1869, with several other smaller ones subservient to it for purification. The aqueduct was built in the time of Sixtus V. (A.D. 1585-1590), but the reservoirs were not completed until the time of Urban VII. or VIII. [1623-44]. From this point the water is carried into the canal or channel through an opening called the _fistula Urbana_, made in a piece of marble. According to Fontana, this water was brought to the Porta Maggiore on a new arcade made out of the materials of the old aqueducts in a very clumsy manner. It was the intention of the Pope to have made use of the canal or conduit of the Aqua Marcia, but that was found to be at too high a level, and his clumsy engineers were obliged to make a new arcade at immense expense. He availed himself, however, of the old arcades as far as he could, by building his new conduit up