This aqueduct was restored by Pope Hadrian I., A.D. 772-795, after it had been damaged by the Goths. It was afterwards repaired by several subsequent pontiffs, especially by Boniface IX., A.D. 1389, and by Nicholas V. in the fifteenth century. It now supplies the fountains in the Piazza Colonna, erected in 1574; at the Pantheon, restored in 1711; several others of the seventeenth century; and that of the _Trevi_, erected by Benedict XIV. in 1730. Near the source of the Virgo passes an abundant stream, also called Marrana; but this has mineral properties, and was therefore carefully avoided in forming the aqueduct for the Virgo. Pliny says[100] that there was a stream which was abhorred by the Virgo, and for that reason the water was called the Virgin. This stream was called by him _Rivus Herculaneus_, some say for its salubrious qualities, because Hercules was the god of health; others because it was a strong stream. There is little doubt that this is the stream here described. The same name of Herculanean is given by Frontinus to the stream now called Marrana[101] in two places, because it was also a strong stream. VII. THE ALSIETINA (A.D. 10), AFTERWARDS MADE THE AQUA PAOLA. Frontinus says of this water, “What could have induced Augustus, that most careful of emperors, to bring in the water of the ALSIETINA (which is called Augusta) I do not well know; for it is not pleasant to the taste, and therefore of no use for the people. It may be, however, that when the work of the Naumachia approached completion, in order not to divert the more wholesome water, he introduced this for the special purpose, and gave the surplus to the adjacent gardens and territories. “It is the custom, however, in the Transtiberine Regio, when the bridges require mending, and there is no water forthcoming from the city side, to make use of this for supplying the public springs, as a matter of necessity. “It begins in the Alsietine lake on the Via Claudia, at the fourteenth milestone, about six miles and a-half off on the right hand. Its course is in length 22 miles, 172 paces, and over arched work 358 paces[102].” “It is the lowest of all as regards the level, supplying only the Transtiberine Regio, and the places adjacent[103].” “The manner of beginning the Alsietine aqueduct is not described in the commentaries, nor can it now be found with certainty; it begins from the Alsietine lake, and then about the _Cariæ_ receives water from the Sabatine lake also, as the Aquarii regulate. The Alsietine gives 392 quinariæ[104].”