The Aqua Sabatina came from the springs which supply the lake Sabatinus, now called di Bracciano (in the Middle Ages it was, and is still often called, Anguillara), on the side opposite to Rome, about twenty-four miles from the city, in a tunnel at a considerable depth. It arrives at the line of the tunnel of the Aqua Alsietina in about three miles. (See Aqueduct VII.)
The line of this aqueduct, which is chiefly subterranean, can be traced backwards by the respirators of Paul V., who repaired it, from his fountain on the Janiculum in Rome across Monte Mario to La Storta, and a little beyond it to the junction of the roads from Viterbo and Bracciano. Here the present road follows a winding course for the sake of better gradients, but the old one (Clodia) followed a more direct line in a cutting through the hill, to the left of the present road, as may be seen by the old paving-stones at intervals; and here, instead of the clumsy respirators of Paul V., are wells only, one of which is near the present road at the junction. The respirators are built over old wells, and serve to shew that Paul V. restored the specus from La Storta to Rome only in this part. There are no respirators beyond that point for some distance, but the specus may still be traced by the wells descending into it. About two miles further on, this specus is carried on an arcade across a valley, and it may be traced from thence to the point where Nibby explored it in 1826, near the lake of Bracciano. From the Osteria Nuova (fifteen miles from Rome) to La Storta (ten miles from Rome), the rough pyramids continue along the line of the aqueduct, and at the Osteria itself there are two of different dimensions close together at the end of the house or castellum aquæ; one is nearly double the size of the other, and both are of very rough construction. Probably one of these is of the time of Trajan, the other of the time of Pope Paul; these wells, with the smaller pyramids over them, are continued to near La Storta; here a change takes place, and the respirators are modern, as has been said.
Procopius expresses his amazement at the quantity of water thus brought to the top of the Janiculum, and poured in torrents over the whole of the region of the Trastevere. This is still the case, and the fountains in front of St. Peter’s and in the gardens of the Vatican, are also supplied from this aqueduct. The water is so abundant that it is even brought over the bridge and supplies a fountain on the other side.
Paul V. also mentions (in his inscription at the fountain above S. Pietro in Montorio) that it had been previously restored by one of his predecessors, Hadrian I., A.D. 774. This was after it had been damaged by the Lombards under Astulfus, as recorded in the Pontifical Registers of Stephen III., Hadrian I., and Gregory IV., in whose time (A.D. 830) the work was completed. The Saracens again destroyed it in 846, and it was again restored by Nicholas I. (A.D. 860). It continued in use in the fifteenth century; but in the sixteenth it was much out of repair, and the branch to the Janiculum almost entirely failed. That to the Vatican continued to flow in 1561, and was repaired by Pius IV., as recorded on an inscription in the garden of the Vatican. In 1618, it had become almost entirely ruined, and was restored in a more thorough manner at great expense by Paul V., a member of the wealthy Borghese family, from whom it is now commonly called the Aqua Paola. The Orsini family, to whom the lake Bracciano belonged, contributed 2,000 ounces of water daily from that lake. Hadrian I., who had made the first great restoration of this water-course, was a Colonna, so that three of the greatest medieval families of Rome have contributed towards it.
The cascade which now falls down the face of the Janiculum, in a specus, turns the water-wheels of three mills in its course; this is mentioned by Procopius, they having been destroyed by the Goths, and their place supplied by other mills made in the Tiber by Belisarius, which continued in use for a long period. The ruins still visible in the river, opposite the mouth of the Cloaca Maxima, are supposed by some to have belonged to these mills. They were of wood only[168], and may have been built on the stone foundations; but these ruins in the river more probably belonged to the fortifications at the head of the Port of Rome, where there was a chain across the river to prevent boats from being carried down by the rapid stream into the Port[169].
Immediately outside of the Porta S. Pancrazio the specus forms the boundary of the beautiful garden of the Villa Pamphili-Doria, on the northern side, for about a mile. It is faced with fine reticulated work of the time of Trajan, excepting where it has been clumsily repaired with brick in the time of Paul V., and it has a wall built upon it. Shortly after passing the limits of the garden, it arrives at the old junction or fork where the stream was divided into two branches, one going to the fountains in front of S. Peter’s and the Vatican, the other to the great fountain rebuilt by Paul V. above S. Pietro in Montorio, as before mentioned. In this part the specus, being above ground, had been much mutilated, and the engineers of Paul V. found it more convenient to change its course and make a new specus for a short distance, than to repair the old one. The ancient reservoir and the fork in the specus were abandoned, and new ones made about a hundred yards off, on rather a higher level. The old reservoir or castellum aquæ was turned into a farm-house, by piercing the walls with windows and doors, and putting on a new roof. The original arrangement for the separation of the great stream into two smaller ones may still be seen in the farm-yard. The old specus is here just below the level of the ground, with its reservoir, but there is an opening into it. A portion of it can also be seen under the Villa Spada, just within the Porta di S. Pancrazio. From the point of junction, or rather of division, to La Storta, and nearly all the way to the lakes, the specus is underground; but the line of the branch added by Trajan can be traced by the respirators as far as the junction, ten miles from Rome, where, in the year 1830, an inscription[170] was found on the Via Claudia, near the tavern of La Storta, stating that Trajan had carried this water into the city at his own expense in A.D. 109. In the inscriptions put up by Paul V. after his repairs, A.D. 1611[171], the Alsietina, Sabatina, and Trajana are all considered as the same.
“In the time of the Emperor Nerva the health of the eternal city was sensibly improved by the increased number of castella, public works and buildings, and cisterns. Nor was his generosity less for the benefit of private individuals, so that those who had previously timidly obtained water in an unlawful manner were now allowed to do so by his favour. Lest some of the waters should perish uselessly great cleanliness was adopted, and there was better ventilation, and the causes of the bad climate for which the city was formerly infamous were removed. I must not pass by the necessity for a new distribution of the waters; but this, with the increased quantity we have added, can easily be arranged, that is, when the work is completed[173].”
These and other passages in the work of Frontinus shew that great works were carrying on under his direction, not then completed, their object being to improve the quality of the water, and to supply an additional quantity in case any of the existing aqueducts should fail, as they did occasionally, and to increase the power of distributing it, with a view to improving the climate. This is a proof that Malaria existed at that time[174], and that the best remedy for it was an abundant supply of water in the hot weather, for which the subterranean aqueducts were most useful. The improvement of the Aqua Alsietina, and the addition of the Sabatina, were not sufficient for both these purposes; and, as they supplied the district of the Trastevere only, this could not be all that was intended by Frontinus in describing the great works begun by him under Nerva, carried on by Trajan, and completed by Hadrian. The only work which will correspond to this account is the great aqueduct called by modern writers the Aqua Alexandrina, and erroneously attributed to Alexander Severus only.
The sources of this aqueduct are about three miles from Gabii in a watery meadow, nearly under La Colonna, the ancient Labicum. The reservoir of the Aqua Felice is in the same meadow, very near that of Hadrian. Several of the springs that supplied that of Hadrian were intercepted by the engineers of the Aqua Felice, who mistook these springs for those of the Aqua Marcia, shewing their ignorance of the line of the aqueducts. One of the streams, which is rapid and has a considerable body of water, is not used, because the water is of bad quality, and is so full of chalk that it is a petrifying stream. The first central castellum and piscina of Hadrian remains nearly intact, lined with the usual brickwork of that period, but much disguised in outward appearance. It is divided in the inside by a rough stone wall, as was frequently the case; the upper chamber to it has an external staircase added, and windows pierced in it, giving it now the appearance of a mere farm-house. Here the specus is perfect, and from hence it goes at first on a substructure, then on an arcade across the fields, and along the line of arcade to the Cento Celle. The part near the reservoir is destroyed, as is the opposite end near that place, but great part of the arcade in the intervening portion remains nearly perfect, and is one of the finest arcades of the aqueducts, extending for miles across the country between the Via Gabina and the Via Labicana. In some places it is double, one arcade over another, to cross a low valley or a stream. At about a quarter of a mile from the source, the specus is open in two places, so that a man can walk along it, being nearly six feet high and three wide. Small openings have been left on the sides of the specus at regular intervals to let the chalky water escape; and in falling from above it has left the marks of a small cascade in each place, in the form of stalactite, a solid deposit of chalk or lime or tartar against the side of the piers, down which it ran. These petrifactions continue all along the line as far as Cento Celle, and near that point there is a part where the stones and bricks of the arcade have been carried away for building-materials, and the masses of hard chalk remain standing up from the ground, in small pyramids, having very much the appearance of concrete respirators belonging to a subterranean aqueduct; but this appearance is deceitful. There is no pipe in them; they are merely petrifactions formed by the deposit of the chalk from the water.
By the side of the line there are some fine piscinæ and reservoirs, of Opus Reticulatum, at intervals, belonging to the time of Trajan or Hadrian. Some of the arches near the sources seem to be earlier. The brickwork is so fine that it appears more like the work of Nero; but most of the work agrees well with the time of Hadrian, and Visconti states that an inscription of Hadrian[175] was found at the reservoir in his time, towards the end of the eighteenth century, and given up to the Borghese family, the proprietors of the ground, who also drained the lake of Gabii, with the aid of Canina the architect. This inscription is believed to have been sold to the French, with other things.
The character of the construction of the castella, or reservoirs, does not agree with the time of Alexander Severus, but suits perfectly well with those of Nerva, Trajan, and Hadrian, whose works are so well known. It is work of the first or second century, not of the third. It does not follow the line of the Via Gabina, but is carried at once to the south of it, towards the Via Labicana, and passes nearly parallel to it between those two roads until it crosses the Via Labicana at five miles from Rome, at the place called Cento Celle.
The bad effect of the petrifying stream was noticed by the engineers of the Aqua Felice, and, as that stream was carefully excluded by them, it now runs to waste through the meadows. This discovery was probably made before the third century, and the specus being then found to be choked up with stalactite, was restored to use on a higher level by Alexander Severus. Although the castella, or reservoirs, are all of the time of Trajan and Hadrian, the specus and the arcade to carry it is of two periods, the later portion of it being of the third century. The principal intention of this aqueduct has been originally to supply the great villa of Hadrian at Cento-Celle, but a branch of it does appear to have been brought into Rome. Although it is very difficult to trace it for the last two miles, this may arise from the general use of all the aqueducts near Rome as quarries, by the engineers of the Aqua Felice. In the excavations made in 1871, in the high ground near the Minerva Medica, between the Porta Maggiore and the Porta di San Lorenzo, by the side of that portion of the Marcian arcade that has been mentioned as found there, was also part of another arcade of an aqueduct of the third century, which may have belonged to this, and it was in that neighbourhood that the inscription belonging to the aqueduct of Severus was found.
About a mile nearer to Rome, at the Torre Pignattara[176], or Mausoleum of S. Helena, there is a branch from the Marrana, passing under the Aqua Marcia, apparently to convey water to an imperial villa. The construction of the arcade of this branch to the south of the road is not of the same period as that of the other arcade on the other side to the north. It is usual for modern topographers, following Fabretti, to consider this branch a continuation of the Aqua Alexandrina; but as the water from the Marrana, which is at a considerably lower level than the Aqua Marcia, runs down the gentle incline of this arcade towards the road and the Mausoleum of S. Helena called Torre Pignattara, this is impossible. The construction is chiefly of the fourth century. The Mausoleum of S. Helena is on lower ground than this part of the Marrana.
Constantine is said to have built a villa for his mother near her tomb; but there are no remains of an imperial villa nearer than those called the Cento Celle, a mile further along the road, or the one called “Torre de’ Schiavi[177],” i.e. Tower of the Slaves, about a mile across country, on another road, but on the same level. A milestone for the third mile, found opposite this mausoleum, with an inscription of the time of Maxentius, has been published by Ciampini. This indicates that some works were going on there at the end of the third century, and the arcade may be of that period.
A large and a very remarkable reservoir of the time of Trajan or Hadrian remains a little to the west of the mausoleum, and on rather higher ground. This was probably to receive the water for a branch to the imperial villa, afterwards taken possession of by the Gordiani, who built at that place their great family mausoleum, on which a tall medieval tower was afterwards erected; of this, very picturesque ruins remain, under the title of Torre de’ Schiavi. There are at the same place other large reservoirs of the time of the Gordiani, shewing that the great imperial villa was still supplied with water from the Marcian aqueduct in the third century.
No water under the name of Hadrian is mentioned in the Regionary Catalogue of the fourth century, it is therefore evident that this great aqueduct was not called then after that emperor, although we are told in his life by Spartianus, that many were made in his time, and were at first called after him (as we have said[178]). At the first reservoir, the starting-point, there was an inscription of Hadrian, and the other reservoirs belonging to it are also constructions of the same period. It may be that this water did not come into Rome at all, but that the aqueduct was made to supply the great villa in the place now called “Cento-Celle,” to which it leads in a direct line, and where it appears to terminate. If any alterations were made, these may have been done in the time of Alexander Severus, and this may now represent the so-called Aqua Alexandrina, as Fabretti thought, although he was certainly mistaken in one part of his account of it. The branch which went by the Mausoleum of S. Helena, and which apparently ran underground to the Villa of the Gordiani, was not a branch of the aqueduct to convey water into Rome, but a branch from the great aqueduct for the villa or villas, as it now does from the Marrana at a lower level. This short arcade is of the time of Constantine. The great and long one that leads to the Cento-Celle is of two periods, the earlier part of the time of Hadrian, the latter of the third century. It is quite possible that the original specus had become choked up with stalactite in the course of a century, and that it was restored to use for a time by Alexander Severus, and so called after him.
It has been mentioned in the account of the Anio Novus (IX.) that, after the main conduit reached the great reservoir at the arch of Dolabella, it was divided into three branches, and that one of these was not completed until the time of Trajan and Hadrian. This important branch was carried over the valley between the Cœlian and the Aventine on a lofty arcade, built upon the agger of Servius Tullius, and over the Aqua Appia, also passing over the Via Appia upon the arch of the Porta Capena to the Piscina Publica. It then ran along the edge of the cliff to the north of S. Balbina, and crossed again the valley between the Pseudo-Aventine and the Aventine itself, a little further to the west, by the side of the road which goes down the hill towards S. Prisca. In the vineyard of S. Prisca a portion of the specus remains perfect, at a very high level[179]. From thence it was carried across the hill to the cliff above the Tiber, where the monastery and garden of S. Sabina are now placed. These are on the site of a palace of the time of the early Empire. Some extensive and important excavations were made there in 1855-57, by the Dominican monks of S. Sabina, and among the discoveries then made were an extensive series of conduits, with a piscina and a nymphæum of the same period,—of the end of the first and the beginning of the second century of the Christian era. A cascade specus served to conduct the surplus water down to the more ancient cave reservoir at the mouth of the Aqua Appia, at the Salaria. An account of these excavations was drawn up by M. Descemet[180], and published in the Memoirs of the Institute of France, with an excellent plan and section. Several brick-stamps, of which the words are given in that work, with the names of the consuls, and some terra cotta water-pipes, with the name of Trajan, were also found here. Others were discovered on the Aventine and near the same spot by Fabretti, who was puzzled by them, because they did not agree with his theories about the aqueducts. Donatus also mentions some of the same facts as known in his time. Some of the bricks were made at the kiln (figlina) of Annius Verus, said to have been on the Aventine, near the Salaria; and, if this is correct, that was the spot where they were found. Others have the stamp of Trajan himself. Another is the work of an Arabian servant of Q. Servilius Pudens, A.D. 139, when the Emperor Antoninus Pius and C. Bruttius Præsens were consuls. A piece of leaden pipe, with an inscription upon it, AQVA TRAIANA, was also found on the Aventine.
The Aqua Aurelia of the Regionary Catalogue must be the one made by Marcus Aurelius to convey water to his villa on the Via Appia, usually called the Villa de’ Quintilii, where a brick-stamp of the time of Marcus Aurelius (A.D. 162) was found on the aqueduct itself by Fea in the eighteenth century[181]. This water was afterwards conveyed to Rome by his successors, Ælius Aurelius Commodus and Septimius Severus, to supply the great thermæ begun by Commodus and finished by Septimius Severus, which were in the first Regio just inside of the Porta Latina, and must have been begun about A.D. 185[182].
The Aurelia was an important aqueduct, and there are slight remains of its piscina just outside of the Porta Latina on the southern side: its specus was traced nearly to that point in the excavations made in 1871. The modern road is cut through this old piscina, forming a foss-way in this portion: the aqueduct there passes underground, and has been destroyed or is not visible in this part; but, about a mile from Rome, it can be seen on the bank in the western cliff of the valley of the Caffarella. The specus remains as a tunnel for a short distance, and this was laid open at both ends in 1872 under my direction; it had been concealed and covered over with Pozzolana sand, which had fallen over it from the cliff above, but it can now be seen again. The greater part of the specus has been destroyed, and used for building the large modern farm-house on the opposite side of the valley, the building material having been good brick. As it would not pay to destroy the tunnel, that was let alone.
These remains of the specus are near the well-known tomb called Dio Ridicolo. To this point it runs along the bottom of the valley at the foot of the hill on the side of the small stream or Marrana, here artificial, and parallel to that branch of the river Almo. This open conduit was probably made in the twelfth century, at the same time that the other branch of the Almo, which runs through Rome, was altered and made into a canal or mill-stream where necessary, in order to keep up a constant supply of water, and to avoid its being wasted in floods.
Let us now trace this aqueduct backwards from Rome, in that part near the city. At the Nymphæum, called the fountain of Egeria, it turns at a sharp angle up to another small castellum aquæ, close to the church of S. Urbano, which is usually mistaken for a tomb; but the walls are lined with opus signinum or coccio pisto, the invariable test of an aqueduct. At this point it turns again towards another fine castellum aquæ, at the end of the Circus of Maxentius and of his son Romulus. It comes on there from the head of the valley of the Caffarella, and to that point from the villa of the Quintilii in the Via Appia Antiqua. Thus far we have traced its course backwards from the thermæ; in order to identify it more clearly, we will now go to the sources, and bring it down to the same point to which we have traced it from the thermæ.
The sources or springs are on the side of the hill of Marino, below Grotta Ferrata, in the same swampy district as those of the river Almo, and of the old aqueducts of the Tepula and the Julia. Several springs are collected into a central reservoir; and, as is usual with other aqueducts, they are then brought into a specus, at first underground to the foot of the hill, then upon an arcade, of which there are considerable remains at the Torre di Mezza, Via di Albano, about seven miles from Rome. This fine arcade of the third century goes on to the villa of the Quintilii, and was no doubt built under Aurelius Commodus, after he had obtained possession of that great and fine villa. In various parts of that great building are remains of reservoirs for this aqueduct, and of baths connected with them[183]. About half-a-mile nearer to Rome is, at an angle, as usual, another large reservoir, which has been turned into a farm-house; and the appearance of a medieval chapel or church has been given to it, by building a tower at one end. Possibly it was used for that purpose in the Middle Ages. From thence to the head of the valley of the Caffarella is but a short distance. Where the specus has been carried on an arcade above ground, it has been destroyed as a quarry for the good old bricks; where the ground is higher and the specus is underground, it has been traced in parts only.
The Thermæ of Septimius Severus and Commodus were close to each other, and probably connected. They are mentioned together in the Regionary Catalogue as in the first Regio, and there are remains of them under the small hill, called Monte d’Oro, probably, from the golden colour of the sand in its original state, which is situated just within the Porta Latina, between that and the Porta Metronia. Some excavations were made there in 1870 by the Archæological Society, and large subterranean chambers and corridors were found similar to those under the Thermæ of Antoninus Caracalla. The specus of an aqueduct was also followed for a considerable distance in the direction of the Porta Latina. This must have been for the Aqua Severiana. Just outside of that gate are remains of two piscinæ or castella aquarum, one on either side, and on different levels. One of these belonged to the Aqua Aurelia, the other to the Severiana. The course of this latter is more doubtful, but it was probably only a branch from one of the great aqueducts, and would appear to have come in the bank on which that part of the wall of Aurelian was built, from the Porta Metronia to the Porta Latina. It arrived at the bridge over the Almo (on which the gateway-arch of the Porta Metronia is built), from the great piscina and castellum aquæ, on the cliff of the Cœlian, near the Porta Capena and the Camenæ, where two aqueducts are now visible, having been brought to light by the excavations of the Archæological Society. The construction of one of these aqueducts agrees with the time of Septimius Severus.
This aqueduct enters Rome at the south-east corner near the Porta di S. Sebastiano, and passes over the arch of Drusus; a part of the arcade is visible by the side of it. The specus can be seen both in the wall of the city, through which it passes, and over that arch, and one of the arches of the arcade remains on the east side of it. It was carried in that manner for some distance across the valley or foss, until it reached the high bank of earth on which the Wall of Aurelian is built, near the Porta di S. Sebastiano, and then along the edge of that bank, which is the great agger of the ancient earthworks, against the outer side of which the Wall of Aurelian is built. The inner side of the bank is supported by a low wall here as in many other parts, and upon or against that inner wall the specus of the aqueduct is carried. It is sometimes on an arcade, in other parts it is carried on the wall to the Thermæ of Antoninus Caracalla. The demolition of part of this arcade in modern times is recorded by contemporary authors.
The specus passed upon an arch over the road in the old foss outside the wall into a garden on the opposite side, where it can be seen on the level of the ground; thence it can be traced through that large garden or vineyard as far as the railway, which passes on the outer side of it in a deep cutting. The remains of the brick arcade here form a wall between this garden and another. It is covered with shrubs, and looks like a hedge, from which circumstance it has hitherto escaped observation. The wall is cut through by the railway, but can be traced on the other side of it along the bank of a narrow deep lane, like what we call in England a Devonshire lane. This lane goes parallel to the Via Latina, on the southern side of it, for about a mile; the aqueduct then leaves it, turning short to the left. Near to this angle, at about half-a-mile outside of the Porta Latina, is a large reservoir belonging to this aqueduct. It is built against the western cliff of the valley of the Caffarella, the top of it level with the summit of the cliff, and therefore is not visible from above, as a person standing on the higher ground looks over it. It is also hidden by a clump of trees; but it is very distinctly visible from the valley below, and from some parts of the Via Appia, and is readily seen to be a castellum aquæ by the boldly-projecting buttresses to support the wall with the weight of water behind it. The Aqua Antoniniana ran along the edge of the cliff, and supplied this large reservoir, which is oblong as usual, and divided down the middle by an arcade, similar to the fine one of the Marcian near Tivoli, and many others. This has been plastered over, and made into a cow-house. It is far above the level of the Aqua Aurelia, which runs below along the side of the valley of the Caffarella. The Aqua Antoniniana clearly came from the higher aqueducts in the main line; and, according to the Einsiedlen Itinerary, it was a branch of the Marcian which went to supply the Thermæ of the Antonines called that of Caracalla. Part of the brick arcade, with the specus upon it, is here visible in another garden against a cliff; it then passes underground for a short distance, but soon emerges again, and can be traced against another cliff as far as the Via Latina, which is here upon a bank, or rather on the edge of higher ground, with the remains of a piscina by the side of it. The specus then again passes underground for some distance, and the next point where we have been able to find it is an old stone quarry, the vault of which fell down in 1870, and revealed this specus, which was not visible before. This is in the garden behind the Albergo de’ Spiriti, on the Via Appia Nova, about two miles from Rome, and near the point where it crosses the old Via Latina[184].
A large reservoir remains near the Porta Furba, about a quarter of a mile nearer to Rome, and just two miles from the Porta Maggiore. Here we excavated (in 1871) this large subterranean reservoir, near the Claudian arcade on the southern side, but not very close to it, rather nearer to the road to Tusculum (Frascati), which passes near the Porta Furba. This reservoir appears to have belonged to the Anio Vetus, which agrees with the account in Frontinus, of a branch of the Anio Vetus at two miles from Rome, going in the direction of a new road. The specus crosses the Via Appia Nova near the Albergo de’ Spiriti, and the Via Appia Nova was probably a new road in the time of Frontinus, as indicated by the tombs of the first century along the side of it.
The Aqua Alexandrina is distinctly mentioned by Lampridius in his life of Alexander Severus (c. 25), as made to bring water to his thermæ, which were near those of Nero, and therefore near the Campus Martius and the Pantheon in Regio IX. This could only have been a branch from the Virgo[185], as there is no aqueduct of the third century along the Cœlian, and no trace of a branch from the Palatine or the Capitol.
There is no probability in the theory of Fabretti, that the great aqueduct coming from Gabii, on the eastern side of Rome[186], was the one mentioned in the life of Alexander Severus as made by him to carry water to his thermæ, near those of Agrippa, in the Campus Martius, on the northern side of Rome. A branch from the Virgo on the Pincian, or from one of the great reservoirs on the eastern side of Rome, could be made at a tenth part of the cost. There is some reason to believe that there was such a branch passing near the Barberini palace.
Another branch may very well have been made from the great aqueducts between the Porta Maggiore and the Porta S. Lorenzo, to the Nymphæum of Alexander Severus, on the Esquiline in Regio V. An inscription relating to this is said to have been found at the piscina in the garden of S. Croce[187]. It is far more probable that this inscription was found on the wall of the great reservoir, on the other side of the Via di S. Maria Maggiore, near the Minerva Medica, where other reservoirs of extensive thermæ of the third century are visible[188]. These were supplied with water from other reservoirs just within the Porta Maggiore belonging to the different aqueducts; the Anio Vetus, the Marcian, and the Claudian, all appear to have contributed their share. The one specially called Alexandrina was probably the lofty one carried upon a tall arcade, from the reservoir of the Claudia near the Baker’s tomb,—forming part of the present city wall. The lower part of the piers of the arcade of this period may be seen built up in the wall; the arches lead to another reservoir between that and the building called the Temple of Minerva Medica, and are there brought to an end, just on the south side of the new arches made for the railway. The specus or conduit, and the arches for it, on these brick piers of the third century, have been rebuilt for the Aqua Felice, in the same rough way as that specus is usually built; but, as that conduit is carried on to the Porta S. Lorenzo in the wall, and as these piers of the third century cease exactly at the point where the conduit of that period would naturally turn off, there seems every probability that this was the Aqua Alexandrina, which was merely a branch from the Claudia and Anio Novus united to supply these thermæ, just as the Aqua Antoniniana was a branch from the Marcia to supply the thermæ of Antoninus Caracalla.
The specus of this branch was carried over the Julia on the Marcian arcade to the point where it terminates, which is exactly in a line with a lofty piscina and castellum aquæ, now a gardener’s house, between the wall and the Minerva Medica, and there are remains of the tall arcade from one to the other; the last pier which joins to that building looks like a large tall buttress to it.
The Temple of Minerva Medica is a brick building of the third century, agreeing with the time of Alexander Severus, and there has evidently been a fountain of importance in the middle of it, with an aqueduct to carry water to it from the large castellum near to it. Upon this castellum aquæ a villa of the sixteenth century has been built; but the vaulted chambers, with the tartar deposit of water, remain in the lower part of this building, and there is a tomb or columbarium of the third century at one end of it.
The dedication of a temple to Minerva Medica, in connection with an aqueduct, is natural, and that this was not an isolated example is shewn by an inscription found near Subiaco[189], and published in 1830 by Martelli, in his work on the Antiquities of Sicily[190]. The Regionary catalogue of the fourth century gives, in the fifth Regio, which contains the Esquiliæ, the Nymphæum of Alexander and the Minerva Medica, all which agrees with the existing remains of this Nymphæum. In the same vineyard, to the north-west or opposite side of the Minerva Medica, and very near to it, are the ruins of another building, called by some “a nymphæum,” now also a gardener’s house, under which the marble pavement remains very evident, the construction belonging to the period of Alexander Severus[191].
Both the Pantheum or hall for the men, and the Nymphæum or hall for the women, had images in the niches round them, and frequently an altar also, so that they were temples at the same time that they were used as waiting-rooms for the baths. The Pantheum of Agrippa was the entrance to his thermæ[192]; the building usually called the Temple of Minerva Medica, from an image found there, is called in the Regionary Catalogue Minerva Medica only. A Nymphæum and a Pantheum equally required a castellum aquæ to supply it with water for the fountains and the stream that ran round it, and there are remains of bath-chambers and niches outside of many of the larger reservoirs, as in this instance.
During some extensive excavations, which were carried on in the spring of 1871 by a company, with a view to building new streets in the eastern part of Rome, considerable remains of the lower part of the walls of these great thermæ of the third century were found on both sides of the road made in the sixteenth century, from S. Maria Maggiore to S. Croce. The company bought two large vineyards, in one of which stands the fine ruin called Minerva Medica, which was evidently one of the halls of the thermæ; the ground is full of ancient reservoirs for water at different levels, some underground, others at a considerable elevation, turned into houses; they may be traced at intervals all along the line within the Wall of Aurelian, from the Porta Maggiore to the Porta S. Lorenzo, which is itself here built against the Marcian arcade, and in one part the outer wall of the large piscina and castellum aquæ of the Tepula is incorporated with the wall, of which it now forms part. This ground had been at one period the Esquiliæ or great burial-ground, and afterwards the garden of Mæcenas, so that remains of great works for the supply of water at different periods were likely to be found there, as was the case.
This aqueduct is said by some to be only a branch from the Aqua Marcia from the castellum or piscina at the Porta S. Lorenzo, to the Thermæ of Diocletian, and to have been made by him. Considerable remains of the large piscina for these Thermæ were found when the railway station was built, a plan and section of it was preserved by Visconti; it was not destroyed, but was built over and effectually hidden. The aqueduct was continued, A.D. 330, by Constantine to his Thermæ on the Quirinal, now in the Colonna gardens. Others say that the Algentiana comes from the Mount Algidus, near Tusculum. In the Campagna between Frascati and Rome, there are remains of large reservoirs or castella aquarum of the third century, which do not appear to belong to any of the aqueducts hitherto described. They are usually said to be only reservoirs for the supply of the adjacent fields; but they are all on the highest points, and it is difficult to see how the water was conveyed to them. There appears to be a regular line of them, not indeed a straight line, (the nature of the country would not admit of that,) but still a line of them at comparatively short intervals, always within sight of one another. It seems probable that the Aqua Algentiana was brought in a subterranean channel or specus from the great reservoir at Tusculum, which is on very high ground, and that the water was permitted to run into these reservoirs at frequent intervals, instead of being carried on an arcade across the country, as had been done in the case of the earlier aqueducts. It is beyond dispute that the ancient Romans were well acquainted with the principle of the syphon, and that they were quite aware that water will rise to its level after a very considerable distance: they may have therefore thought it expedient in this aqueduct to avail themselves of that principle. It is difficult to explain how water could be supplied to these numerous high reservoirs in any other manner.
This stream was brought into Rome in the bed or foss of the river Almo (Flumen Almonis), mentioned in the Regionary Catalogue as in Regio I., and not otherwise accounted for in this enumeration. The water now comes from the Marrana, which has its source near Marino, and from the Aqua Crabra, which comes from Rocca di Papa, near the lake of Albano, some miles further up the hill; the waters of these two streams are united before a part of them is carried through the tunnel of the Aqua Julia to a point of junction with the bed of one of the many branches of the small river Almo. The Almo itself comes also from the hill of Marino, but from a different part of it, and is divided into many branches when it arrives on the low ground of the Campagna. One of these was made use of for this mill-stream, a canal being carried in banks of clay in straight lines, where the old bed of the river passed through low ground, and had been therefore liable to floods; but this old bed or foss was used, to save expense, where it passed through higher ground in its old winding course.
Originally that part of the branch which passes through Rome was alternately wet and dry, as many of the other branches are, and was liable to floods after heavy rains. The main branch of the Almo turns off to the south near the Torre Fiscale, following nearly the same line as the cross-road from the Via Appia Nova to the Via Appia Antiqua, and passing under this road twice. In this part of its course it is generally dry in dry weather; but when it arrives at the head of the valley of the Caffarella, several other springs that never fail run into this old deep foss. One comes from near the villa of the Quintilii, another is called the fountain of Egeria, a third the Aqua Santa, from its medicinal qualities. There is a bath-house built over that spring. The original springs on the hill of Marino bring little water in dry weather, not more than sufficient to supply ponds near to them for the cattle; but, in wet weather, the water runs off in the old deep winding foss, which also drains all that part of the country.
The sources of the Marrana are about a mile above Marino, and nearly three miles from Albano; they are in a long, narrow, deep valley in the rocks, and the water gushes out in several places at short intervals on both sides of this valley, which continues on under the rock on which the small town of Marino is built. Close under the town is a tall medieval tower, and at the foot of this is a piscina of rude early character, the lower chamber of which is still full of water. A specus cut in the rock as a tunnel is also visible at this point. On the side of the valley opposite to the town are the splendid ancient quarries of peperino, called by Vitruvius lapis Albanus, because Marino was in the district of Alba Longa. The stream flows on in the same deep valley, winding down the hill, and, at the foot of it, the Aqua Crabra, coming from Rocca di Papa, is united with it shortly before it is crossed by the bridge on the road to Grotta Ferrata, ten miles from Rome and near the tunnel through which flows part of the united water, the main body going on straight to the river Anio; the part which is carried through the tunnel turns at a sharp angle to the left, or west, towards Rome. At each end of the tunnel is a loch of early character, partly cut in the rock and partly built of travertine, with the grooves of flood-gates. Over the exit from the tunnel is a piece of old wall faced with Opus Reticulatum, of the same rude early character as that of the Aqua Julia.
After the water emerges from the tunnel, it passes in a deep bed to a bridge over the stream of the Marrana, near the piscinæ, six miles from Rome. At this point the deep foss of the river Almo is close to it. This is dry in dry weather, but has abundance of water in wet weather, and here the foss is dammed across; this appears to have been done originally to effect a junction with the water of the Marrana, which from this point flows in the foss of one of the many branches of the Almo that intersect the Campagna in this part. This mountain-stream is a very uncertain one; sometimes the deep foss is full of water, flowing at the rate of five or six miles an hour, at other times it is dry. Numerous winding streams are collected into one at the head of the valley of the Caffarella, near the church of S. Urbano. Here it passes through swampy ground at a place called Aqua Santa, on the cross-road from the Via Appia Nova to the Via Appia Antiqua; here also several springs fall into the deep bed, one of which is miscalled the fountain of Egeria[193]. In dry weather this branch of the river Almo appears to begin here, and from thence to the mouth of this branch near S. Paul’s, mentioned by S. Gregory as the Almo, the water never fails. All the other branches are deep, dry fosses after dry weather, and the branch that now flows through Rome must originally have been frequently dry, and at other times liable to floods[194].
To remedy this evil, a branch was made from the stream, consisting of the Marrana and Aqua Crabra united, which never fails; and, in those parts where the water passes over low ground liable to be flooded, it is carried in a bank of clay covered with sand, and planted with canes. In such a bank it is carried from near the ford in the natural bed of the river at Roma Vecchia to the Torre Fiscale. Between these two points there is a loch with a flood-gate and a lasher, over which the water falls into one of the deep beds or fosses of the Almo; but this deep bed of a mountain-stream has no other beginning than this same stream, here raised in a bank of clay, into which the water of the Marrana has been turned. In other parts where the ground is high, and consequently the water is below the level of the ground, it follows its ancient, natural, winding course in a deep foss. This is the case both near the original point of junction before reaching the ford at Roma Vecchia, again after passing the Porta Furba, and again under the walls of Rome near the Lateran. From Roma Vecchia, passing by the Torre Fiscale to the Porta Furba, it is carried in a bank of clay many feet above the level of the meadows; but after passing the Porta Furba, it again falls into the old deep foss for about a mile at the foot of the Claudian arcade, winding about sometimes on one side, sometimes on the other, then near to a part of the road to Frascati. For the last half-mile to the Porta S. Giovanni, this road is modern on a large bank of earth across the valley or great foss outside the Wall of Aurelian, and for most part of this line the Marrana is carried in a small bank of clay against the side of the larger bank of the road; but before it reaches Rome it falls again, that is, the earth rises on the terrace under the wall, and the Marrana falls into the old deep bed near the Porta Asinaria, after passing through two mills built on bridges, one on the line of the old Via Asinaria, the other of the old Via Lateranensis.
This small stream enters Rome under the Porta Metronia, which is built on a bridge over it[195]. This bridge has a brick arch of the time of the early Empire, partly concealed by a medieval arch in front of it. Shortly after entering Rome the stream passes at the north end of what is now the nursery-ground of the city, called Orto Botanico, and under a bridge on which another mill is built; by the side of it is the road into that large garden, known to have been that of Crassipes, the son-in-law of Cicero, who mentions in one of his letters a flood of this stream carrying wooden shops from the bank in front of it to the Piscina Publica[196].
This is exactly the direction that the stream takes, as it turns at a sharp angle to the north directly after crossing the Via Appia, and passes close to the Piscina Publica; while the Tiber flows from north to south, and a flood of that river would have carried the shops the other way (if it reached that level at all). There is another mill near the angle on the Via Appia. The stream then passes along a curve at the southern end of the Circus Maximus, (washing the foot of a lime-kiln,) then under the slope of the Aventine and through the gas-works on the site of the Carceres of the Circus, then underground and through another mill in the Via della Marrana near the Bocca della Verità. The eighth and last mill is on the bank of the Tiber, and is built over the mouth of the stream, the back of the building resting on the old tufa wall, called the Pulchrum Littus of the Kings, in which an aperture was left for the Almo when that wall was built. The front of the mill is built on medieval arches standing in the bed of the Tiber.
This alteration of the bed of the Almo may have been made at an early period, of which we have no record, and restored to use in 1124, under Pope Calixtus II., or it may have been entirely made out of the remains of the old aqueducts at that time. We have distinct records of the work done then; but in one of these the expression used is reduxit, that is, he “led again” the water from the old arches. In any case, a great benefit to the city was made at that time, and the account of it fairly belongs to the history of the aqueducts, from which it was made. The following account of it is given by the Cardinal of Arragon, in the time of Pope Calixtus II., A.D. 1124:—