villa, seen towering within the walls. This brings us to the confused mass of material which flanks the gate of S. Lorenzo, being also a tower of the fifteenth century.

We have here the inscription of Honorius, although much defaced, upon which the system we have adopted mainly depends for its authority; and we have an illustration of the words contained in it, "egestis immensis ruderibus." The gate is nearly upon its original level; but the aqueduct against which it is placed is interred up to the spring of the arch. This aqueduct conveyed the three streams called Marcia, Julia, and Tepula, of which more will be said in our general account of the aqueducts. In the mean time we may observe the entablature of the arch rent in many places, but still showing the inscriptions of Augustus, Titus, and Caracalla *: also by going within the gate, we shall see the ancient channel which conveyed the waters above named: and it will be worth while to notice its direction towards the succeeding gate, the remains of the aqueduct, which may be traced along the walls, and the final adjusting of the whole by Sixtus V.; for in the same direction, but in a new and higher channel, runs now the Acqua Felice, which we see turning from the walls, near the second tower from the gate, to go towards the Piazza di Termini, The Porta S. Lorenzo can be no other than the Porta Tiburtina, where the road began which led to Tibur. This was the same as the Via Valeria, which, passing through Tivoli and Vicovaro and Carseoli, arrived at Itri (Hadria), the same destination as that of the Via Salaria.

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The high tower which flanks the left side of the entrance is of the fifteenth century, and bears the arms of two cardinals. The lower part of one of its sides is built of ancient stones, originally formed for other purposes; and on one is an inscription turned upside down. Next succeeds a wall of Sixtus V., coeval of course with his aqueduct, which runs along it; and after another tower of the same century, we arrive at one of Honorius, which is the hundredth, reckoning from the Muro Torto. The next bears the initials of Nicolas V.

After examining the first hundred towers and the intervening curtains of wall, in this detailed manner, any one will be able to discriminate for himself the various epochs of the construction of the rest; we shall now, therefore, be less minute in our descriptions.

From the point at which we are now supposed to have arrived, to the Porta Maggiore, there occur fourteen towers, for the most part of that brick construction which we assign to the age of Honorius, and some restorations of Clement XI. and others. After passing the first four towers of the fourteen, we begin to discover in the lower part of the walls some brick-work of a superior kind, not unworthy of the age of Nero or Trajan; and a little farther will be observed some modillions projecting from the curtain, and some traces of conduits, but the whole announcing a fabric of considerable extent. The close adjoining aqueduct immediately suggests that this may have been a "castellum aquæ," which was taken into the line of walls by Honorius; but

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as we may also discern brick-work of another date, and that seemingly unconnected with the design of the "castellum," we very probably in this place have come upon the original line of Aurelian's walls. Soon after we shall find a closed postern, resembling in its construction the P. Chiusa.

Just before arriving at the Porta Maggiore, a misshapen tower, built of fragments of marble, and of travertine ornaments, projects at an angle; and underneath it we see the channel (specus) of an old aqueduct, built of square blocks of peperine stone; and looking on the opposite side of the road under the hedge of the vineyard, we discern some further vestiges of it: at present it will be enough to fix the attention upon this subterraneous aqueduct, by observing it conveyed the water called the Anio Vetus. Afterturning the angle of the patched tower, we see, taken into the walls, the flank of an arch made of peperine stone, and within the gate exist the remains of two arches of the same material and fabric; in the upper part of this flank or pilaster are seen three distinct channels, rising one above another 40, the lowest of them received the "Aqua Marcia," the middle one the Tepula, and the highest the Julia; and we have already seen how the same three streams arrived at the Porta S. Lorenzo. Underneath the tower which stands on the left of the gate in entering is another

40 See Fig. 1. in the annexed sketch; which is here introduced for the sake of convenience, although belonging to the subject of the aqueducts. It is taken from a drawing in Camucci, which was made before the Porta Labicana was walled up, and when the whole was free from the encumbrance of modern buildings.

channel resembling that of the Anio Vetus, but tending in a different direction. This is considered as a branch taken from the "Anio Vetus" by Augustus, and is the "specus Octavianus," which conveyed water into the twelfth region. It will be necessary to bear this also in mind, as we shall meet with further traces of it in continuing our circuit. Independently of the five aqueducts here enumerated, we have yet two more which especially claim our attention, for to them belongs the lofty frontispiece against which the two gates of Honorius were placed. At the end of the frieze which bears the large inscriptions will be seen the two channels: the highest is the Anio Novus, and the other the "Aqua Claudia." The imposing aspect which the emperor Claudius here gave to his aqueducts was because they came across two public roads, the one leading to Præneste, the other to Labicum. The elevations of this building on both sides are precisely the same; but it is necessary to divest them of the rude works of Honorius, before we can come at the design: then we shall find the whole was formed of two large arches, and relieved by three blank windows, supported by Corinthian columns, and covered by a pediment. They are more remarkable for their proportions than for their elegance. Above these come the three inscriptions to which we shall afterwards have recourse: the highest belongs to Claudius, the middle one to Vespasian, and the lowest to Titus.* By a reference to our sketch of this noble monument, the elevation will be easily understood. The two great arches stood