Chapter X: Appendix: Aqueducts (2)

Between this building and the gate, but within the wall, though on the bank on which it stands, are slight remains of another _castellum aquæ_, supposed to have been for the Julia (Nos. 26, 869, 1873), which has its external face in the direction of the wall, and must have been concealed by it when that was built. This is also of the first century, as is shewn by the brickwork, and it seems to have been a _castellum aquæ_ by the disproportional size of the buttresses used to support the weight of the water, one of the invariable marks of such a structure. The other mark is the peculiar cement with which the wall is lined, called _Opus Signinum_ in Latin, _Coccio Pesto_ in Italian, which is made of broken pottery, and is the hardest cement that is known; it is often impossible to break it, even after it has been exposed to the weather for centuries.

A plan and section of the ground between the two gates, called by Frontinus Esquilina (S. Lorenzo) and Viminalis (Maggiore), shew the difference of level, and the three aqueducts passing underground in the middle between the two gates, and carried on arches at both ends near the gates (see No. 1938*).

The plan of the ground at the sources of the Tepula and Julia is given in 1980*.

VI. THE VIRGO (NOW CALLED AQUA DI TREVI) WAS MADE IN THE YEAR OF ROME 732, B.C. 21.

This aqueduct has its sources in the meadows of Lucullus, on the banks of the river Anio, on the old Via Collatia, eight miles from Rome, about a mile further than the Aqua Appia, not at the same level, but comparatively near the surface. There are several springs, each of which has its own separate reservoir just below the surface of the ground; in some of them the vault is scarcely perceived. These are also called conduit-heads (864, 863, 862). From each of these small reservoirs a conduit runs into the central reservoir (860, 861), which is considerably larger, circular in form, surrounded by a wall, lined with the cement called _coccio pesto_, and one part of this central reservoir under the road now remains. This is near Salone, with its medieval tower. (See the Plan, 1155*.)

From this large central reservoir the surplus water is carried off by short conduits into the country ditches, and so into the river Anio. The main _specus_ into Rome begins at the central reservoir, and runs generally underground along the line of the old Via Collatina, now called Lunghezza. The course of the aqueduct can be clearly traced by the small pyramidal or conical structures over the wells at regular intervals, called Respirators (660*), or which might have been called Ventilators, as they give air to the _specus_ below. It runs in the high bank of the old road for two or three miles, behind the ruin called Torre d’ Scavi, supposed to be the Thermæ of the Gordiani, in a direct line towards the Porta Maggiore; but about half-a-mile before arriving there, it turns sharp to the north along the bank of the great _foss_ or valley, and being underground is traced by the Respirators. Further to the north, beyond S. Agnes, at some little distance, the old line can be traced in the catacomb of S. Priscilla on the Via Salaria, where the _specus_ is visible, half filled up with the deposit of clay (1109*, 1466). In the road on the bank on which the Wall of Aurelian is built, near the Porta Salaria, it can be traced by the low arcade at the foot of the wall which is built upon it (5).

But when the line was altered, it was carried still further to the north, and it enters Rome under the garden of the French Academy (the Villa Medici); it here is marked by two _cippi_ (2088, 2089), with inscriptions upon them, and under the garden is a large reservoir very deep, level with the ground in the great foss on the outside, and with the Campus Martius inside the walls. It was then divided into two branches, one of which went along the Via de Condotti, the other along the Via del Nazzareno (83, 1108*) to the Fountain of Trevi, rebuilt in A.D. 1735 (1356); originally, it went to the north end of the Septa, near the Pantheon. Some remains of this were shewn in 1871 in the Piazza di S. Ignazio (2326). The _specus_ can be seen, with an inscription upon it recording repairs by the Emperor Claudius (82), in the yard behind a house near the Palazzo del Buffalo.

The plan of the ground at the sources of the Aqua Virgo (or de Trevi), is given in 1968*, and Sections of it in 1979*.

VII. THE ALSEATINA.

This aqueduct was made by Augustus in the year of Rome 763, A.D. 10, to bring water for his great Naumachia, or sham naval battles in the Trastevere; the water was not good for drinking[228]. It was brought from the lake called Alseatina, in the hills on the western side of Rome. It is altogether distinct from the great series of aqueducts on the eastern side. The source can be seen in the bank of the lake, and the _specus_ or subterranean conduit can now be entered, the water of the lake having recently been drained, and reduced to a much lower level.

To these was added from another lake about three miles distant from the Alseatina, another branch called the Sabatina. The two conduits were united after a few miles near the old city of Cariæ, at a _castellum aquæ_ or reservoir, now made into a house, and called the Osteria Nuova. The Alseatina was at the lowest level of all the aqueducts, and it is now very difficult to see any remains of it, except the _specus_ in the lake at its source.

Trajan afterwards adopted the Aqua Sabatina, but omitted the Alseatina, and carried the Sabatina at the highest level instead of the lowest (see Aqua Sabatina, Aqueduct X.) Pope Paul V., who restored these aqueducts to use, went back to the Alseatina lake, and his _specus_ can be seen there on a different side of the lake to that of Augustus; both are now left dry. There is, near the junction at the Osteria Nuova, a remarkable flight of steps for the use of the _aquarii_, or the men who had charge of the aqueducts. It passes through the upper _specus_, and goes down to the lower one (No. 2959*). The respirators of these two lines can be seen and traced; they are of a different size and form. The two can be seen close together at the Osteria Nuova (No. 2960*). The _specus_ is also seen in No. 2961*.

VIII. THE CLAUDIA, AND IX. THE ANIO NOVUS, A.D. 38-52.

These two aqueducts were made together, or were so closely connected that we cannot separate their history, although they were not the same water; the Anio Novus came from some miles higher up the river Anio than the Claudia. The latter was, like the previous aqueducts, taken from springs, that were intercepted before they fell into the river Anio; but the Anio Novus was part of the river itself, in which a gigantic loch was made by building a great wall across it, about a hundred yards in front of a natural waterfall, and forcing the water to flow over it, forming a magnificent cascade, and at the same time causing some of the water to flow through the _specus_ which was cut in the cliff by the side of the river, at a rather lower level than the top of the wall. The sources of the Claudia are below this cascade, those of the Anio Novus are above it. The line of each of these aqueducts is distinct in all the early part of its course; but after they come down to the valley of the Campagna of Rome, at the Piscinæ, the two are carried on the same fine lofty arcade into Rome.

These were the highest, and passed over the Marcian arcade with the three aqueducts upon it. They form the finest feature in the landscape on the eastern side of Rome. The sources are above Subiaco, and in what is considered by artists as some of the most picturesque scenery in the world. The photographs illustrating this are very numerous, the subjects being some of the best that can be imagined for this purpose. The history of these two most important aqueducts can now be better seen in this series of photographs than in any other manner, and better understood than by any written description of them, after the outline of their history is once given.

They were begun in the year of Rome 789, A.D. 38, under the Emperor Caius Cæsar, or Caligula; carried on and completed by his successor, Claudius, in the year of Rome 803, A.D. 52. They were therefore fourteen years in construction, according to Frontinus[229]; but Nero was then married to Octavia, he was the actual governor of Rome, and he carried on the great work upon what are called the Arches of Nero, along the Cœlian Hill, as far as the arch of Dolabella, where a large reservoir for this water was built. This work was afterwards carried on by his successors in three branches, one to the Colosseum, a second to the Palatine, and over it to the Capitol, and a third to the Aventine. Frontinus himself, who has left us his admirable treatise on the subject, had the direction of these works for many years; he was Curator Aquarum under the Emperors Nerva and Trajan, and some of the greatest works were done in his time,—at his suggestion, and according to his plans.

Some of the sources of the Claudia were in the lake of S. Lucia, below Subiaco, between that and Vico Varo (see 1536). In its course through the hills the _specus_ is almost entirely underground, and cannot be shewn in photographs; but the line of its course is shewn in the map of the aqueducts from Rome to Subiaco, reduced by photography in Nos. 1967* to 1984*, especially in Nos. 1976*, 1978*, 1979*, 1981*. It crosses mountain streams on the bridges called Ponte Lupo (1532) and Ponte di S. Antonio (1530); and an inscription relating to it, of _A.D._ 88, is given in No. 1976*.

When it reaches the level ground of the Campagna, nearly on the same level as the hills of Rome, the _piscina_ for it is subterranean, and only the summit of this is visible, looking like a _tumulus_ only (688); but from this the _specus_ is seen to emerge, at first only just above ground, but gradually getting higher (or the soil, in fact, is getting lower), until it is carried on the grand series of arches or arcades across the country, which remain nearly perfect for some miles, as far as the Sette Bassi and Roma Vecchia. In 1002, a long line of this arcade is shewn with the Claudian _specus_ upon it, and the Anio Novus over that in many places; the two can readily be distinguished, by the Claudian being built of large blocks of stone (with the edges chamfered off), and the Anio Novus being faced generally with brick, occasionally with _opus reticulatum_. Nearer to Rome, this fine arcade has been very much damaged, or carried off altogether as building material by the farmers, and by the engineers of Pope Sixtus V. to build the Aqua Felice; but some portions of the old arcade remain, and are shewn in No. 1006, where the distinction between the two _specus_ comes out very clearly. In 1005, two of the brick arches with which it had been strengthened by Trajan are shewn, the stone-work having all been carried away.

In 689*, a plan and section of the Torre Fiscale is shewn, with the crossing of six aqueducts. 528 is a view of this tower and of the arches of the aqueducts crossing each other under it, with the Aqua Felice in the background. 529 shews the arch of the Claudia separately, and the construction of it, with the Aqua Felice passing under this arch of the Claudia. 530 gives very distinctly the arch of the Marcia, Tepula, and Julia, with that of the Claudia passing over it. 531 and 532 are more distant and general views of that tower, and the aqueducts passing under it. 1439 is a side view of it, and of the old tombs on the Via Latina in that part. 1004 shews the arches of the Claudia and Anio Novus in perspective, and the opening into the _specus_ of the Claudia. In 550, another fine portion of the arcade is shewn, with brickwork of Trajan. The Porta Furba and a long line of the arcade is seen in the distance. 548 shews the Porta Furba at another crossing, with the fountain, and a portion of the arcade of the Felice; with the Marrana in the bed of the river Almo passing under it.

62 is a portion of the Claudian arcade, about half a mile nearer to Rome, with the arches filled up with brickwork of the time of Trajan; at this point there is another crossing. 63 shews a portion of the brickwork of Trajan, originally built to strengthen the stone arcade; but the latter has been carried away by the engineers of the Felice. 549 shews some interesting repairs of the time of Nero, with massive square buttresses faced with reticulated work. 70 is a medieval tower at the angle of the garden of the Sessorian Palace, now of the monastery of S. Croce, near the point where the aqueduct enters the wall.

547 shews the interior of the Tower and a _piscina_, at the entrance into Rome, the four chambers of which are visible, the inner wall of this tower having been destroyed; and into the interior of this the water of the Claudia entered in the first chamber and went out at the fourth. This photograph also shews the remains of a large _castellum aquæ_, now forming part of the Wall of Rome, on the north side of the garden, with a continuation of the arcade in the Wall of Rome in this part. In 544 the _specus_ of the Claudia is plainly visible on the top of the wall, and remains of the Anio Novus over it. In the distance are seen some of the arches of Nero, across the valley and foss (?), from the angle near the Porta Maggiore to the Cœlian Hill. This garden might very naturally be called by Lampridius “The Garden of the Specus,” for the _specus_ in the time of the Emperors must have been the most conspicuous object in it, or visible from it (542).

412 shews another of these reservoirs in the same garden, with repairs in brick by Trajan. The arcade of the Aqua Felice, built against the outside of the Wall, is also seen through the arches of the Claudia.

31. The exterior of the Porta Maggiore, with the _specus_ over it, the lower one the Claudia, the upper one the Anio Novus. (The inscription of A.D. 404 is given in 1872.) Under these, but still on the top of the wall, the _specus_ of the Aqua Felice may be seen, built as usual of rough stone concrete. To the right or north of this may be seen the three _specus_ of the Marcia, Tepula, and Julia, passing through the wall in the opposite direction, now under the Felice, and originally under the Claudia and Anio Novus. These three _specus_ are carried upon one of the piers of the Marcian arcade, built into the great wall. Just beyond these, further to the right, is part of the last tower of the Claudian arcade.

32. The Porta Maggiore, with the _specus_ on it, seen sideways, and the north side of the Baker’s tomb.

The last tower and _piscina_ of the Aqua Claudia; it stands at an angle of the wall projecting from it, and shews clearly that it stood there when the wall was built by Aurelian, and then incorporated into it. When the fortifications of Honorius at this gate were destroyed in 1833, the inscription relating to the aqueduct was preserved and built up to the right or south of the gate (shewn in 1872). Within the wall, behind the tower, is a large reservoir or _castellum aquæ_, of which there are slight remains, shewn in 967 and 968.

A panoramic view of the line of the Claudian arcade, on the north side of the Sessorian gardens, taken from the extreme end of them at the west, is shewn in Nos. 542 and 543. On the left hand is the beginning of the arches of Nero, going across the foss towards the Cœlian; then the Porta Maggiore is seen sideways, with the two _specus_ on the top of it. Under this is part of one of the two great reservoirs believed to have been the Gemelli of Frontinus. Then comes the western wall of the Sessorian gardens, rebuilt by S. Helena, the construction being of the time of Constantine. To the extreme right is the ruin of the Basilica or Great Hall of the Sessorian Palace, repaired by him. This is miscalled a temple of Venus and Cupid on some of the maps.

Having thus traced the Aqua Claudia from its sources into Rome, we must now do the same for THE ANIO NOVUS, which in its early part is distinct from it, as we have said.

1514. Sources of the Anio Novus above Subiaco. The river Anio in the highest point, with which the aqueducts are connected, is seen winding through a gorge in the rocky mountain, with remains of the bars or dams, across the river, forming the two upper lakes or lochs. The celebrated monasteries of S. Scholastica and S. Benedict are visible on the hill to the left.

1515. The River Anio, a little lower down, with remains of the second barrage or dam across it, forming the third loch or lake, with the modern bridge built upon the ruins of the old wall that formed the bar. Chapels of the monks of S. Benedict are visible on the hill to the right.

1534. The Bridge of S. Francis, over one of the branches of the Anio that meet near the rocks before mentioned, above Subiaco.

1517. Remains of a great reservoir or _castellum aquæ_, of the time of Trajan, on the bank of the lake or loch before mentioned. The wall is faced with _opus reticulatum_, with layers of brick at intervals, the usual construction of the time of Trajan.

1518. The modern bridge, far below, and remains of the old high wall on which it is built, are seen under it; below are the cliffs of the third lake or loch, cut into a circular form. In the bed of the stream are large stones fallen from the wall or bar across the river.

1519. Remains of another _castellum aquæ_ above Subiaco, and the mouth of a cave connected with the aqueduct.

1555. _Specus_ of the Anio Novus cut in the cliff of the valley of the Anio. This is below the level of the great bar, and the water was forced to go through the _specus_ into Rome by the bar being higher than the _specus_. A modern winding road has now been cut here, and the rock has been in part cut away, shewing an opening into the _specus_, which is six feet high and two feet wide. Above is seen a tower and an embattled wall of the modern Villa Gori.

1516. Part of the _specus_ of Trajan, who repaired this aqueduct. The _specus_ is cut as a tunnel in the cliff, with a reservoir by the side of it.

1556. A view of the gorge in the mountains above Subiaco, where the three lakes are situated.

1536. A small lake at the source of the spring called Fons Novus Antoninianus, one of the sources of the Anio Novus.

1558. Cascade at the Paper Mill, on the site of a _piscina_ of the Anio Novus, above Subiaco.

1057. Arches of the bridges of the Marcia and Anio Novus, in the Valley of the Arches above Tivoli.

1052. Arch of the bridge on the Anio Novus, in the Valley of the Arches above Tivoli, with a medieval tower built upon it, forming one of the most picturesque objects in the neighbourhood of Rome.

1522. Specus of the Anio Novus below Tivoli, on the road to Garciano, called the Promenade, with openings into it, and an old tomb in front of it. This promenade is through an olive wood, and the roots of the olive trees run into many of the ruins.

1523. One side of a _castellum aquæ_ of the aqueduct above the road to Garciano, faced with _opus reticulatum_.

1529. A bridge across a valley that passes the road to Garciano. This bridge is above the road on the left, in the valley called the Arcinelli.

1531. Ponte de S. Antonio, a fine bridge for the aqueduct below Tivoli, across a gorge. It is seen from above looking down upon it, with the chapel of S. Antony at the end of it, and a medieval castle in the distance. The road for horses, and the remains of the _specus_ by the side of it, are here visible.

1532. Ponte Lupo, near Poli, west side, below Tivoli, the finest of all the bridges of the aqueducts. It crosses a valley from one cliff to the other, and is a solid wall for part of the way, the rest on arches. The two _specus_ are here visible, as seen from below on the west side.

687. Arrived in the valley of the Campagna, the great _piscina_ of the Anio Novus and that of the Claudia, which is near to it, is underground, and the summit of it only is visible, appearing like a tumulus. It is near the old Via Latina, and below the present roads to Albano, Frascati and Marino.

74 and 75. After leaving the great _piscinæ_, the two _specus_ are carried on the fine arcade, of which a panoramic view is here given, shewing its general effect for some miles.

554. Passing by the remains of Roma Vecchia to the Torre Fiscale and the Porta Furba (given under the head of the Aqua Claudia), the _specus_ rises to a remarkable reservoir, which from its great elevation must have belonged to the highest of the aqueducts. It is a most picturesque one, near the Mausoleum of S. Helena, but is earlier than her time; it belongs rather to that of Trajan, being faced with fine reticulated work, with layers of bricks on the exterior. The interior is distinguished by remarkably solid central buttresses, to support the wall against the pressure of the water (553).

926. Another large reservoir of the same period and style, and at nearly the same level; it occurs about a mile further from the main line of the aqueducts, at the place called Torre de’ Scavi, where the Thermæ of the Gordiani were afterwards made. This appears also to have belonged to the Anio Novus, as no other aqueduct is high enough for the water to have reached it.

ARCHES OF NERO.

At the great reservoir inside the Porta Maggiore (the Porta Esquilina of Frontinus), the water of the Claudia and the Anio Novus was united for the general use of the City. This aqueduct entered on the highest ground in Rome, and the water supplied the deficiencies of any of the other aqueducts in case of need. Being a part of the river Anio, it never failed. It was forced to come through Rome, as has been shewn by the arrangements in the bed of the Anio above Subiaco. This united water was carried to all the fourteen Regiones of Rome, and in order to ensure an abundant supply, it was conveyed in the great stone _specus_, on the fine arches of Nero along the whole length of the Cœlian Hill for more than a mile; at the west end of the Cœlian an enormous reservoir was built for it on the level of the _specus_ at the top of these arches, so that the base of the reservoir was fifty feet from the ground, and the road passed under it. From this great central reservoir, at a very high level, the water was distributed in various directions.

Before arriving at the Cœlian Hill, it had to be conveyed to and along the Cœliolum (now the Lateran Hill). It had come through the gardens of the Sessorium, as we have seen, in the two separate _specus_, after it had entered Rome at the extreme eastern corner, on the north side of these gardens, which are nearly half a mile long. These are _the palace gardens_ mentioned by Frontinus. The Sessorium with its gardens (now the monastery of S. Croce in Gerusalemme) had been one of the two Prætorian camps, this one being at the south end of the great _agger_ of the Tarquins, which formed the outer _mœnia_ of Rome on the eastern side. The one, called the Prætorian Camp, is at the north end of the same great bank.

Each of these fortified camps was surrounded by a great wide and deep foss or trench. These great banks and trenches are usually mistaken for natural hills and valleys; but natural hills and valleys are not merely high banks fifty feet high and perhaps a hundred feet wide, nor are natural valleys long narrow trenches of the same dimensions, running on each side of the great banks, being in fact the trenches from which the earth has been thrown to form the banks. Such a bank with such trenches can be clearly traced all round Rome by eyes that are accustomed to examine such things, although modern buildings have disguised them so much that an ordinary observer does not see them. People cannot see over modern walls of twelve feet high, still less over the great Wall of Aurelian fifty feet high, and they do not think of comparing the level of the ground on each side of that wall, nor can they easily do so. These great ancient earthworks were extremely convenient for the engineers of the Aqueducts, which were brought upon the high banks at the farthest corner. They were carried along the bank on the north side of the Sessorium, from its north-east corner to the south-west angle, where the great bank of the Tarquins joins on to it. Some branches of the Aqueducts, perhaps the main stream in some cases, were then carried along this high bank of the Tarquins to the north, as far as the other Prætorian Camp, and beyond it along the outer wall of Rome, as we have seen in the case of the Anio Vetus, the Marcia, Tepula, and Julia. These did not pass through the Sessorium, but parallel to it about a hundred yards on the north of it. The Claudian arcade had been at about that distance on the north of it, all the way from the Piscinæ into Rome. The Marcian arcade was made nearly over the Anio Vetus, which ran between that arcade and the Claudian, but much nearer to the Marcian.

On entering Rome, this main stream went straight on through the great bank to the large reservoir on the inner side. The reservoirs for the Tepula and Julia were much to the north, near the Porta di S. Lorenzo (the Porta Viminalis of Frontinus), as we have seen; that of the Marcia was much closer to the Porta Esquilina. The two great reservoirs, called by Frontinus the Gemelli, were made in the great foss between the Sessorium (S. Croce) and the Cœliolum (the Lateran). They had probably been originally made for the Aqua Appia and the Anio Vetus, being both at a low level, though one was much deeper than the other. Advantage was taken of these ancient reservoirs to erect the higher one required for the reception of the waters of the Claudia and Anio Novus over it, or by the side of it, as was very usual throughout Rome. The later reservoirs are always made nearly over the old ones. This is equally the case here at the entrance into Rome and at the other end of the Cœlian. The great high reservoir of Nero is close by the side of, and really over, the great subterranean reservoir of the Aqua Appia (now under the garden of the Villa Cœlimontiana, as described in the account of the Appia).

The foregoing explanation seems necessary to explain the photographs that now follow, belonging to the Arches of Nero. The first of these (No. 77) shews the junction with the Porta Maggiore; the two _specus_ that pass over that great gate are visible to the right of the photograph. The beginning of the Arches of Nero is then seen, where they have to cross the great wide and deep foss of the Sessorium, and were therefore strengthened by sub-arches, as seen in No. 76. A more close view of these arches, nearly at the same point, is seen in 66.

These arches were used by the engineers of the Aqua Felice whenever they suited their purpose, and cut about or destroyed without mercy; they also made use of an old _specus_ to carry their metal pipes whenever it was convenient to do so, and the _old specus_ that ran along the Cœlian was very convenient for that purpose. 1295* is from a drawing made to shew this. The _specus_ of the Aqua Felice was first carried on the lower arches of the double arcade of Nero, the upper part of the arcade being destroyed. The metal pipes were then carried down into the old subterranean _specus_ (_the Specus Vetus_ of Frontinus). This is in the same garden or vineyard as the Gemelli, in the great foss between the Sessorium and the end of one of the banks of the Tarquins, (on which the garden of the Villa Volkonski has been made, and along which the Arches of Nero run.) A portion of the grand arcade, with the _specus_ very visible on the top of it, is shewn in 759. This is close to the Scala Santa of the Lateran; the arcade carrying the aqueduct passed along the bank on the north side of the Lateran fortress on the Cœliolum, and supplied that with water.

On the western side of the Lateran fortress is another great foss, between the Cœliolum and the east end of the Cœlian Hill. It was either thought more convenient to make a bank across that great foss for the aqueduct to rest upon, or this bank which traverses that great foss had been made before for an upper road, and was used first for the Aqua Appia and the Anio Vetus, and afterwards by Nero. The existence of such a foss between the east end of the Cœlian Hill and the Cœliolum is denied by those who have not paid attention to the subject, and have not been into the gardens and vineyards to examine it; but the fact is a matter of demonstration. The tomb of the first century (miscalled the House of Verus, probably a tomb of the great Lateran family), being on the western bank of that fortress and the eastern bank of the foss, and the other tomb of the first century also, in the garden of what was the Museum of Campana (_under_ an arch that carries the modern road), on the western side of that great foss, are a demonstration that there was such a foss on the east side of the City of Servius Tullius, i.e. that the Cœliolum and Lateran did not form part of the City at that time. (See my chapter on the Tombs, and the photographs of these two tombs, 174 and 1942).

The Arches of Nero remain on the Cœlian in many parts of the line, by the side of the road from the Lateran to S. Stefano Rotondo and the Navicella, with the arch of Dolabella, which was under the great reservoir of Nero, and formed the entrance of the Claudium. The Arches of Nero are faced with the finest brickwork in the world (ten bricks to the foot, as usual at that period, and are chosen as typical examples). This is well shewn in 78, and the internal construction of rubble, faced only with the fine brickwork, in 358. A line of these, shewing the picturesque effect, is shewn in 131 and 357. The aqueduct formed one of the usual angles between the Lateran and the arch at the west end of the Cœlian. It has been destroyed in this part; but this accounts for the arches being sometimes on one side of the road and sometimes on the other.

We have now arrived at the arch of Dolabella, built when he was consul, A.D. 10, as an entrance to that part of the Cœlian Hill which had been the keep when it was a separate fortress, and was afterwards made the Claudium. This arch is of very simple construction, of travertine, the same construction as the early part of the Basilica Julia, built by Julius Cæsar and Augustus. It was used by the engineers of Nero as a foundation for their great reservoir, or rather for one corner of it, as we clearly see in 72. The work of the time of Nero terminated here, but the design was carried on by his immediate successors. The water was then divided into three branches; the one on the right hand, to the north, went to the great reservoir between the Cœlian and the Esquiline, called the _Stagna Neronis_, and was used for the sham naval battles. Around these Stagna the Colosseum was afterwards built. A portion of the arcade on which the _specus_ was carried is visible in the garden of the monks called the Passionists of SS. John and Paul, and is well shewn in No. 1773, looking towards the east, with the ruins of the reservoir over the arch of Dolabella, and the church of S. Stefano Rotondo in the distance. There are remains of a reservoir for this, of the third century, in the garden of the monks on the terrace of the Claudium, opposite to the Palatine, shewn in No. 1765. The ruins of the fine arcade of the Claudium stand on this terrace; the _specus_ also is in a wall here, behind the arcade. A portion of another reservoir or _piscina_ for them can be seen at the foot of the cliff of the Claudium, at its north-east corner, opposite that part of the Colosseum near the Meta Sudans; this is also shewn in No. 1743, with _opus reticulatum_ of the time of Nero. This branch continued in use in the third century; for there are remains of another reservoir for it, again at the foot of the Claudium opposite to the Colosseum, but more to the east, near the north-east corner of the Claudium, and near to the eastern end of the Colosseum. The remains of this reservoir are shewn in No. 1735. A colonnade carrying the _specus_ from this reservoir to the second story of the Colosseum, is shewn on one of the coins of Septimius Severus, who probably built this reservoir. In the corridors of the Colosseum are open stone troughs lined with the cement for water. These carried water from this aqueduct in a constant running stream to cool the air. They are work of the third century, with old inscriptions on some of them, shewing that they were made of old materials.

Another branch from the great reservoir went straight across to the Palatine, and from thence to the Capitol; it first follows the line of the road down the Clivus Scauri, on the left or southern side, and a fragment of it is visible opposite to the church of SS. John and Paul, as seen in No. 305. At the foot of the Clivus Scauri it formed an angle, and passed against the cliff on which the apse of the church was afterwards built; it now forms the lowest and last of the series of arches that are carried across the road to support the side of the church. Then, after this angle to the north, it resumes its course to the west upon the arches across the valley to the Palatine, which was a double arcade; but the lowest tier of it only remains, as is shewn in 116. A portion of the upper tier is also visible at the end of it; an arch of this upper tier remains, which, having been made into a back gate of the Palatine, has been suffered to remain, and is shewn in No. 72. A large reservoir for it was made at the south-west corner of the Palatine, on which the palace of Commodus was afterwards built; part of this reservoir and _specus_ is shewn in 683 (made from a drawing). The _specus_ went across the middle of the Palatine, and has been found more than once in some of the recent excavations, but not understood. It was then carried on the bridge of Caligula to the Capitol, a small portion of which remains connected with his palace, as is shewn in Nos. 1447 and 1451.

The third branch from the great reservoir over the arch of Dolabella on the Cœlian was made in the time of Trajan, to carry water to supply the thermæ on the Aventine, called after Sura, the cousin of the Emperor; these thermæ were closely connected with the private house of his family, rebuilt in his time, and called in the Regionary Catalogue “Privata Trajani,” of which there are considerable remains, now subterranean. The first place where this branch of the aqueduct is visible is in another reservoir (1147) against the cliff of the Cœlian, opposite to S. Balbina. This is partly above the level of the hill, and has been thought part of the Palace of Commodus, on the Cœlian (which may possibly have been built over it, but the existing remains are of the time of Trajan). The lower part is under this, and is excavated in the cliff. These were brought to light in the excavations of A.D. 1868 (559, 1008, 1009, 1010, 1011). The plan and section of it are to be seen in 1150*, 692*. Against the cliff the aqueduct formed one of the usual angles towards the north, and this was carried across the valley on the _agger_ or bank of Servius Tullius, first passing over the arch of the gate of the Porta Capena, above the Aqua Appia, on a much higher level, and on an arcade, probably a double arcade, like the Arches of Nero near the Porta Maggiore, on account of the great height at which the water had to be carried from one hill to the other. All that remains of this lofty arcade is a line of brick piers passing across from the Cœlian to the Aventine, over the Aqua Appia, before described, and passing by the north end of the Piscina Publica, as rebuilt in the time of Trajan over the old one, which had belonged to the older aqueducts. There are considerable remains of the walls of this period, that divided the chambers shewn in 557, 558, 1288.

This arcade can then be traced against the cliff of the Pseudo-Aventine, on the north side of S. Balbina, though partly concealed by the filling up of the space against the cliff before mentioned. The tall arcade then crosses the valley from the Pseudo-Aventine to the other part of the Aventine, and from the garden of S. Balbina to that of S. Prisca, and, in the latter garden, there are considerable remains of it on the cliff opposite to the Palatine. At the north end is the _specus_ upon the arcade (the top is open, and there is a walk upon it), 79. A small portion of the Thermæ of Sura is also shewn, with the _specus_ in front of the ancient wall of tufa, called the Wall of the Latins (833).

From the _piscina_ and reservoir on the cliff of the Cœlian another branch went to the south, over the spring of the Camenæ (?) 692, and near that of Egeria (?); it was carried over the Porta Metronia, and on the bank of the City Wall as far as the Porta Latina.

Another fine arcade of the time of Nero (No. 1317) leads to the Nymphæum before mentioned, where the Trophies of Marius were hung. The elevation shews that this water must have come from the highest of the aqueducts, the Anio Novus; and the remains of the reservoir near the Porta di S. Lorenzo, supposed to have been for the Aqua Julia, being on high ground, may have been for this branch, which conveyed water to the Thermæ of Titus.

X. SABATINA TRAJANA.

Great works for the aqueducts were carried on in the time of Trajan. One great work of his time was to bring water from the lake Sabatina to the top of the Janiculum. Augustus had previously brought water from that lake, supplementary to his aqueduct, from the lake Alseatina (VII.), to supply his Naumachia in the Trastevere; but the Aqueduct of Augustus was on the lowest level, that of Trajan on the highest. It does not appear that Trajan made use of the old _specus_ of Augustus; but his aqueduct was afterwards made use of by the engineers of Pope Paul V. for the Aqua Paola, although they also brought a branch to it from the Alseatina, as Augustus had done.

That of Trajan is chiefly subterranean, and has been described under the head of the Alseatina (VII.), but nearer Rome it is above ground, and is carried on an arcade against the wall of the Villa Pamphili-Doria, near the Porta di S. Pancratio. Both the arcade and the _specus_ are faced with the _opus reticulatum_ of that period. (664* is from a drawing, 1065 from nature.) In some parts, one side of the _specus_ has been cut away (1063). Just on the outside of that garden a large _castellum aquæ_ of this aqueduct has been made into a farm-house, and in the yard of that house a branch from it can be seen (665*), apparently for the purpose of irrigation; or, as some think, this was formerly the point of division, one branch going to the Vatican, the other to the great fountain on the Janiculum (960), above S. Pietro in Montorio. The division now takes place at a short distance from this point. Procopius, writing in the sixth century, admires the enormous quantity of water brought by this aqueduct to the highest point in Rome; as it descends the hill, it turns the wheels of the flour-mills. After it arrived at the low level of the ground in the Trastevere, the respirators of the pipes for this aqueduct are carried in tall pyramids resembling chimneys (540). Part of the arcade and _specus_ rebuilt by Paul V., near the garden before mentioned, is shewn in 1064, with the inscription of A.D. 1609 above it.

XI. HADRIANA (?), TRAJANA (?) OR ALEXANDRINA (?).

The next great work of the period of Trajan or of Hadrian, on the eastern side of Rome, was probably begun in the time of Trajan. It brought water from springs under Labicum, now La Colonna, the same that is now brought for the Aqua Felice. The water from several springs was collected in a central reservoir, on which an inscription of Hadrian was found by E. Q. Visconti in the eighteenth century. This is between Pantana and Gabii, in the valley under La Colonna (1540). There are several other reservoirs of the time of Trajan or Hadrian along the line (1637, 1638). This aqueduct was considered by Fabretti to be of the time of Alexander Severus, and since his time it has usually been called the Aqua Alexandrina. It may have been partly rebuilt and brought into use again in his time, after having been choked up with stalactite, one of the springs used proving to be a petrifying spring.

Near the sources this arcade is low and much damaged, and the _specus_ where it remains is nearly filled up with stalactite (1541, 1542). In some parts of the line the stalactite has all the appearance of a petrified cascade, and is evidently formed by the water oozing out and dripping and petrifying as it fell (1436). Further on there is a fine arcade for it across the country in the direction of Cento-Celle; and in some places the arcade is double to raise the _specus_ to the necessary level, as in the Arches of Nero (1428, 1429). A portion of the arcade, where it is broken off, is seen in 1427, with the tower of Cento-Celle in the distance. Another portion of this fine arcade is shewn in 1640. It is of two periods; the upper part is of the third century, and may have been rebuilt by Alexander Severus (as has been said). At Cento-Celle the ground is high, and the aqueduct passes underground for some distance, along the side of the road towards Rome.

About a mile nearer to Rome, there is a branch aqueduct from the foot of the Marcian arcade, in the direction of the Mausoleum of S. Helena, which Fabretti considers as part of the same aqueduct; but it is difficult to see upon what grounds. There is a fine arcade here also for about a quarter of a mile; but it is of the time of Constantine, and I have not been able to trace any connection between this and the other. This arcade has been originally double, and the lower one only now remains, with a modern _specus_ made upon it (555 and 556); but the water now flows _from_ the Marrana, at the foot of the arcade of the great aqueducts, which were here on higher ground, and _runs down_ upon this arcade to the garden and small monastery of S. Peter and Marcellinus, at the Mausoleum of S. Helena, called the Torre Pignattara, from the earthenware pots of which the vault was made.

XII. AURELIA, A.D. 185, AND XIII. SEVERIANA, A.D. 190.

These two aqueducts were made to convey water to the Thermæ of Commodus and Severus in Regio I., of which the remains were found in the excavations of 1870, just within the Porta Latina. The first part was originally made by Marcus Aurelius, for the use of his great villa on the Via Appia, called the Villa dei Quintilii, and the great reservoir and thermæ connected with it remain (2346, 2349, 2350, 2351, 2352). From thence it was brought into Rome by his successor, Ælius Aurelius Commodus. The water came from the Alban hills, near Marino (2358, 2359, 2360, 2361, 2362, 2363), at first underground, and then on an arcade, of which there are considerable remains near the Torre di Mezza Via di Albano (1626 and 1627).

From the Villa dei Quintilii it went parallel to the Via Appia. One of the reservoirs of it nearer to Rome is made into a farm-house, with a tower to it, and has the appearance of a church at a little distance; it is called the Casale di S. Maria Nuova (2348); it then passed again underground. Near the head of the valley of the Caffarella there remains a _piscina_ for it nearly perfect (1372); this is very near also to the Circus of Maxentius and his son Romulus. There is another _piscina_ or small reservoir for it near the church of S. Urbano, often mistaken for a tomb; here it again forms an angle, and the _specus_ descends (plan and drawing, 831*) to the Nymphæum, or so-called Fountain of Egeria (262). The _specus_ is then continued in the cliff of the valley of the Caffarella, from that fountain towards the tomb of the first century called Dio Ridicolo. Nearly opposite to that tomb the _specus_ is visible in the cliff, with large openings into it, between which it passes underground. Wherever it was above ground it has been carried off as building materials and destroyed, so that it has not again been found until it arrives at the remains of a _piscina_, just to the south of the Porta Latina (984). It then entered the city of Aurelian through the bank on which his wall is built, and supplied the Thermæ of Commodus within that gate (as has been said), 1485, 1486.

XIV. ANTONINIANA, A.D. 215.

This aqueduct was used to supply the great Thermæ of the Antonines, now called after Antoninus Caracalla. It is more easily traced backwards, passing along the inner side of the bank on which the Wall of Aurelian is built, then upon an arcade which has been destroyed in this part, but of which remains are visible inside of the Porta Ardeatina (986), by the side of the Arch of Drusus, just within the Porta di S. Sebastiano (73, 1772, 1202). It then passes underground through the bank, and emerges in the city wall at the angle between the Porta di S. Sebastiano and the Porta Latina (539, 883). It here crosses the road, and is visible in the garden on the opposite side (884).

XV. ALEXANDRINA, A.D. 225.

The Aqua Alexandrina is mentioned by Lampridius in his life of Alexander Severus, but it was probably a branch from the Anio Novus only, as the Nymphæum engraved on one of his coins[230] has been identified with the ruins near S. Maria Maggiore (2126, 2127). This stands on very high ground, and the only aqueduct that could reach it was that of the Anio Novus. This branch can be traced in the wall by the piers of the arcade, which have been built into the Wall of Aurelian near the Porta Maggiore (80 A, B). The _specus_ and the arches were destroyed by the engineers of the Aqua Felice; the piers only remain, and these cease just before we arrive at the point where the railway now enters Rome through the wall (99). They come to an end directly in a line with a large reservoir, now a gardener’s house, near the Minerva Medica, almost between that and the wall, but a little to the south of it; one pier, however, of the tall arcade of the third century remains, as a sort of buttress, against that side of the fine building of the same period called the Temple of Minerva Medica (537). There are great remains of thermæ and fountains in the large vineyard in which this building stands. Some of these are of an earlier period; but a considerable part of them are of the third century, and of the time of Alexander Severus. The Nymphæum before mentioned was at the north end, and is a fine picturesque ruin, with very evident remains of the aqueduct in it (61, 963, 964). The water was here divided into several branches, of which we see portions of the _specus_ going in different directions. One of the most important of these goes to the great reservoir of the Thermæ of Titus and Trajan, called the Sette Sale. This was made long before the time of Alexander Severus, who only rebuilt the Nymphæum; and there is an arcade of the first century leading to this Nymphæum from a reservoir near the Porta di S. Lorenzo.

At a short distance to the south of this celebrated Nymphæum is another very curious reservoir, now in a very bad state, having been turned into a gardener’s house, but which must have been of considerable importance, and probably belonged to the thermæ of the third century (2322, 2323). There is a _cippus_ with an inscription, which indicates that the building was a _castellum aquæ_ (2324).

XVI. ALGENTIANA, A.D. 300.

This aqueduct was made to supply the great Thermæ of Diocletian on the Viminal Hill, but is believed to have been entirely subterranean, so that little is known about it. There was a reservoir for it on the eastern side of the Thermæ, under the present railway station. Drawings and a plan of this were preserved by Visconti[231].

XVII. THE AQUA CRABRA, THE MARRANA, A.D. 1124, AND THE RIVER ALMO.