RESERVOIR ON THE ARCHES OF NERO OVER THE ARCH OF DOLABELLA. [Illustration: AQUEDUCTS—ON ARCHES OF NERO. OVER THE ARCH OF DOLABELLA] This Plate is almost a repetition of Plate XV., but from a different point of view, and this great reservoir is of so much importance for the history of the aqueducts in Rome, that it was necessary to shew it as clearly as possible. Without repeating what has been said before, we may add that the arch seen to the right in this view is the beginning of an arcade which led to the Colosseum. Another branch in a more direct line led to the Palatine, after passing first along the north wall of the garden of the Villa Celimontana, then by the western side of the Clivus Scauri, parallel to the church of SS. John and Paul, and at the foot of the hill passing across the road, and under the apse of the church; then turning again southwards on an arcade across the valley to the Palatine, of which there are remains; afterwards passing along the whole length of the Palatine underground, it is visible at the mouth of a tunnel on the platform opposite to the Capitoline Hill, and went across the Forum Romanum over the bridge of Caligula. The work of Nero stopped at the Arch of Dolabella, but it was taken up and completed by his successors. Another branch went also to the left, on the west wall of the garden of the Villa Celimontana, to the valley between the Cœlian and the Aventine. There is a large reservoir for it on the cliff of the Cœlian, partly below and partly above it, and in the garden of the monks of S. Gregory. It then went on a tall arcade, over the Porta Capena and the _agger_ of Servius Tullius, to the Piscina Publica, and from thence, again crossing the valley between the two parts of the Aventine, to the Thermæ of Sura, and the private house of Trajan, and the temples on the edge of the Aventine, and to the mouth of the aqueducts in the cave under the Priorato at the Porta Trigemina, and so to the Tiber. THE AQUEDUCTS. DESCRIPTION OF THE DIAGRAMS. PLATE I. PLAN OF THE SOURCES OF THE APPIA (I.) AND VIRGO[232] (VI.) [Illustration: I. AQUEDUCTS—AQUA APPIA AND VIRGO. PLAN OF THE SPRINGS AT THE SOURCES IN THE MEADOWS OF LUCULLUS, ON THE BANK OF THE RIVER ANIO, EXCAVATED IN 1868] 1. Farm-house of Cervaro. 2. —— Cervelletta. 3. —— La Rustica. 4. —— Salone. 5. Church. 6. Sources of the Aqua Appia. 7. —— Virgo. 8. —— Augusta. 9. Tombs. 10. Aqueduct of the Virgo. 11. Road of Cervaro. 12. —— La Rustica. 13. —— Prænestina (?). 14. —— Collatia. 15. Bed of the stream of the Fontanille. 16. —— of Tor Sapienza. 17. —— of Ponte Nono, the Rivus Herculaneus. 18. Direction of the Aqueduct of the Appia. 19. Stone-quarry of Collatium and Necropolis. PLATE II. [Illustration: II. AQUEDUCTS—AQUA APPIA, SPECUS. IN A TOWER OF THE PORTA CAPENA, UNDER THE CŒLIAN, NOW A GARDENER’S COTTAGE, EXCAVATED IN 1868.]