Quitting the in-door life of the Roman, let us turn our attention to other monuments of labor and art, which are no less remarkable. Foremost among these stand the sewers and aqueducts of Rome. So thoroughly was the drainage of the city provided for, that the ground was tunneled through and through with arched passages; and Pliny’s expression, “the hanging city,” is literally correct. The most important of the sewers was built under the rule of the elder Tarquin, and planned in a spirit prophetic of future greatness. It is composed of three concentric arches, forming a channel of fourteen feet in diameter, and proportional height. This was the main trunk, into which was discharged the drainage flowing through a multitude of subterranean channels, together with the vast surplus quantity of water from the aqueducts used to cleanse the net-work of drains. A cart loaded with hay could be driven down the main passages, and Agrippa is said to have performed a sanitary voyage in a boat through the main sewers, when superintending their repair.

More attractive, though not more useful, monuments of labor and care for the public health, remain in the aqueducts, by which a plentiful supply of water was always insured to the city of the seven hills—the mere dilapidated remains of which still suffice for her present use. A mere glance at the proportions of some of these noble works, which conveyed the purifying and health-giving element, through hills and across valleys, from sources varying in distance from sixty miles downward, may well raise a blush at the scant and meagre substitutes which we can show in the nineteenth century. Well may Frontinus, in an exulting tone, compare the useful splendor of the nine aqueducts, which in his time supplied the city, with the useless, slave-grown bulk of the pyramids, or the merely decorative works of Grecian towns.

The most remarkable of the nine aqueducts were the Anio Vetus, the Aqua Marcia, the Aqua Claudia, and the Anio Novus. The Anio Vetus brought a supply from the river Anio, a distance of forty miles. It was built B. C. 273, and consisted of a stone water-course, the channel of which was coated with cement. A still longer one was the Aqua Marcia, extending along a distance of fifty-four miles, six and a half miles being above ground, and chiefly supported on arches. So lofty was the level of the terminal reservoir, that the highest parts of the Capitoline Mount could be supplied from it. This aqueduct united toward its termination with two others, in the same pile of masonry, so as to form one range of building, in which the three water-courses occupied different levels, one above the other, and finally discharged their streams into the same reservoir. At the same period that this aqueduct was constructed, 700 wells, 150 springs, and 130 subordinate reservoirs, were added to the former sources of supply. The Marcian Aqueduct was remarkable for the vastness and solidity of its proportions and construction.

Augustus caused an aqueduct to be built specially for the purpose of supplying the vast basin in which he exhibited sham naval fights to the citizens: but the Anio Novus, one of two new aqueducts built by the Emperor Claudius, was the most striking of all in its architectural effect. For six miles before its entrance into the city the water flowed along a channel supported by arches, some of which reached the height of 109 feet, and constituted a range of great beauty.

When an aqueduct was to be constructed, the first step consisted in forming a large basin at the source of the supply. In this the liquid rested to deposit its impurities, and for a similar purpose the channel was expanded into other reservoirs at various intervals along its course. The channel in which the water flowed was formed of stone or brick, covered with a layer of cement. The slope of the water-course, according to Pliny, was only one quarter of an inch in every hundred feet, but Vitruvius makes it six inches in the same distance. It probably varied with circumstances. An arched covering excluded the sun, and vent-holes in the sides or top provided for a free circulation of air. From the castella or reservoirs lying along the course of the channel, adjacent lands were sometimes irrigated. From the terminal reservoir the water was conveyed to its various destinations through pipes of metal or earthenware. These terminal reservoirs were works of great size and solidity. One such at Cuma is 200 feet long by 130 wide, and is covered in by a vaulted roof resting on four rows of pillars. At Rome there were 247 subordinate basins, in which the water from the terminal reservoirs of the various aqueducts was collected, previously to passing to the baths and houses. A staff of officers and a body of laborers were specially provided to keep the aqueducts in repair.

In their mining operations and in the formation of some aqueducts, we have seen that the ancients were obliged to tunnel. But their most remarkable works of this kind are the subterranean passages, by which the Romans drained many large lakes. One such channel, through which the lake Fucino discharged its water, is still nearly perfect. It is more than three miles long, one mile of the distance being carried through the hardest rock, under a mountain 1000 feet in height. Perpendicular and lateral shafts were sunk into the tunnel for the convenience of working, and 30,000 men were employed on the spot at the same time. Where the tunnel passes through earth it in vaulted with brick.

After the aqueducts the baths follow in a natural order. The great fondness of the Greeks and Romans for ablution, which the warmth of their climate rendered a great luxury, early led to ample provision for bathing, both public and private. Both people were familiar with the use of the hot-air bath, which was especially employed by the Spartans; but the warm-water bath, succeeded often by the cold douche, or plunging bath, was most usual. All the appliances that could minister to comfort and luxury in this department were not only known but common; and to such a degree did the splendor of the public baths at Rome attain, that it was not unusual for emperors themselves to bathe amid a throng of meaner citizens. Lofty, vaulted rooms, lighted by glass, with temperatures artificially contrived to suit the different states of the bather; spacious basins, lined with marble, and fitted with marble, bronze, or even silver benches, were plentifully supplied with water, hot, cold, pure, or scented with the most precious perfumes and essences. Porticoes and vestibules adorned with finished works of art, where the bather took his exercise listening to the recitations of poets, the declamation of orators, or the subtle disputes of philosophy; or perhaps reclined in luxurious ease amid the pleasant murmur of adjacent fountains; cool avenues for the promenaders at mid-day, lawns, terraces, and all the best efforts of their ornamental gardening, were united in the Roman ThermÆ, or great public establishments for bathing and recreation, planned and executed in the imperial city and provincial towns. One of these, the ThermÆ of Caracalla, was more than a mile in circuit.

The water for the baths was heated in brick furnaces, consisting of two rows of cells arranged over the fire, with which the lower row was in contact, while the upper row received the water from the branch of the aqueduct furnishing the supply. Pipes from the lower cells led into the baths, and these pipes were surrounded by flues, in order that the water should not cool in its transit. The party-walls between the cells of the furnace were also traversed by flues, in order to economize fuel as much as possible. Private baths, on a smaller scale, were attached to every house of consequence; and were favorite places for the display of the owner’s wealth.

The theatres of both nations were constructed with great skill, and especial adaptation to the ends of sight and hearing. They were generally built on the side of a hill, and sometimes, in Greece, literally hewn out of the solid rock. Some were of vast size; the ruins of one at Argos, semi-circular in form, inclose an area 450 feet in diameter. The seats for spectators were arranged in ascending stages, and the outer wall of the structure, behind the topmost row of spectators, was surmounted by a kind of portico, in order to throw back the sound of the actor’s voice. The semi-circular included space was the “orchestra,” where the chorus danced on a boarded floor. The stage, of course, closed the opening of the semi-circle, and was approached from the orchestra by steps. The back of the stage was bounded by a lofty screen, which in the theatre built of wood during the Ædileship of M. Æmil. Scaurus was composed of three different substances—the bottom of white marble, the centre of glass, and the highest of gilt wood. The early theatres of Rome were built of wood, but after the time of Pompey stone was universally employed. The art of scene-painting was well understood, and various machines were employed on the stage for instantly changing the scene, or for introducing the actors flying in mid-air.

The amphitheatres of Rome, so called from being as it were double theatres, formed a complete circle, or rather an ellipse. They, too, like theatres, were built of wood, until the time of Augustus, from which period they gradually increased in size and splendor, until Vespasian and Titus caused the crowning work of the kind—the ColisÆum—to be erected for the convenience of the immense crowds of sight-seers flocking to the public games. This most celebrated remain of Roman architectural art covers five acres of ground; the longer diameter being 615 feet, and the shorter 510. Four orders of columns, the first pure Doric, the second Ionic, the third Corinthian, and the fourth, Corinthian pilasters, rise one above the other till they attain the great elevation of 160 feet. These columns have one-fourth of their thickness buried in the face of the wall which they ornament. There are eighty columns in each tier, and from their summits spring arches supporting the tier above. There were, therefore, four tiers of seats for the accommodation of spectators, and this sufficiently explains how the building could contain the immense number of 87,000. The numbers contained by these buildings of antiquity were very large; the Attic theatre held 50,000, and the wooden theatre of Scaurus, before-mentioned, could accommodate 80,000.

We have mentioned that the perfect arch was not known to the Greeks; indeed, they have no word for it in their language. But the frequent use of the arch by the Romans, even in walls, where plain masonry would have sufficed, shows it to have been a favorite form of construction, and the triumphal arches built to commemorate victories are among their most splendid remains. Those erected by Drusus, Titus, Septimius Severus, Gallienus, and Constantine, still remain, and with the bas-reliefs commemorative of the events which they were designed to perpetuate still attest the great amount of Roman skill, and the extent of Roman conquests.

Another class of buildings—the basilicÆ, exchanges or law courts, are highly interesting from the fact that they were afterward converted into Christian churches. One such edifice was always placed in the forum for the convenience of traders. It was generally of oblong shape, the length being from two to three times greater than the breadth. The earlier edifices of the kind were mere peristyles, or open spaces inclosed by columns, but subsequently the open space was defended by walls—the columns still remaining for ornament. Small private chambers were cut off from one end, for the use of the law officers and merchants; the main area was divided into a nave and two side-aisles. At one extremity of the central nave was placed the tribunal of the judge, which stood within the oblong area so long as the original use of the building merely as a law-court continued; but afterward, when the same edifice was used as an exchange, a semi-circular space was thrown out at one end, and the tribunal placed within this, in order that the seat of justice might not be disturbed by the noise of traffic. The advocates and jurors occupied the space within the semi-circle, while persons interested in the cause were accommodated with side-seats. The columns of the side-aisles supported a gallery, from which rose other columns sustaining a roof usually flat in the centre, and arched down to the supports so as to resemble the shell of the tortoise.

It may, perhaps, seem strange, that in our notice of so many ancient buildings we have not once alluded to temples. The reason for this course is, that no description could be given of such structures without necessitating an account of orders, styles, and proportion, into which our subject does not strictly enter. But the peculiar use of marble in constructing the roofs of temples may be well alluded to in this place. Slabs of this material were employed and fixed, much in the same manner as earthen tiles; descending in parallel rows from the ridge of the roof to the eaves. Bronze, afterward gilt, was also used for the same purpose.

The Greek and Roman towns were generally irregular in plan; their streets narrow and mean, even in Rome, till the great fire in Nero’s reign; after which the city was rebuilt with great regularity. The increasing value of land led to the erection of many-storied houses in the main streets; but the houses of the wealthy were always chiefly composed of ground-floor apartments, wherever space permitted. This subject, and the house-carpentry generally of the ancients, is involved in some obscurity.