LINE OF THE SPECUS OF THE ANIO NOVUS. It is here carried in the cliff of the valley of the river Anio, seen on the left of the picture. Both of these views are continuations of those seen in Plate IV., and one helps to explain the other. The _specus_ continued in this way for many miles underground, in one sense, when seen from above, but not underground when seen from below. When it has to cross the mouths of the small subsidiary streams that fall into the Anio, it has to be carried over bridges or arches, at other times it is cut in the rock or cliff. PLATE VI. THE CLAUDIA, ANIO VETUS, AND NOVUS, AND MARCIA IN THE VALLEY OF THE ARCHES ABOVE TIVOLI. [Illustration: AQUEDUCTS—CLAUDIA AND ANIO-NOVUS. IN THE VALLEY OF THE ARCHES, NEAR TIVOLI.] This valley is about two miles above Tivoli, where there is a junction of another stream with the Anio, in rather a wider valley than the usual valley of the Anio only. One arch of the lofty Claudian arcade is left on the side of the valley next Tivoli, and on the top of this a medieval tower has been built, which has an extremely picturesque effect. Through the arch may be seen a small portion of the Marcian arcade, and at a few yards to the left the Anio Vetus, which there passes half-underground at the foot of the tall arcade of the Anio Novus. PLATE VII. [Illustration: AQUEDUCTS ABOVE TIVOLI ANIO NOVUS. MEDIEVAL TOWER IN THE VALLEY OF THE ARCHES _Photogravure Dujardin, Paris_] TWO OTHER VIEWS OF THE RUINS OF THE ARCADES OF THE CLAUDIA AND ANIO NOVUS, in the Valley of the Arches above Tivoli. In the foreground, the Marcian seen through the arch, and the Anio Vetus again through the arch of the Marcian. These views are celebrated for their picturesque character, as indeed is all the country about Tivoli and Subiaco. PLATE VIII. AQUEDUCTS AT TIVOLI. CASCADES OF THE ANIO, WITH THE ROUND TEMPLE OF THE SIBYL AT THE TOP. [Illustration: AQUEDUCTS AT TIVOLI TEMPLE OF THE SIBYL AND CASCADES CASCADES OF THE ANIO] This cascade shews the character of the country through which the aqueducts had to be carried, but the waters of the aqueducts taken out of the river Anio were necessarily confined each within its own _specus_, here in tunnels, which are carried in a zig-zag course gradually down the hill to the level of the Villa of Hadrian in the valley below. PLATE IX. AQUEDUCTS BELOW TIVOLI. [Illustration: AQUEDUCTS BELOW TIVOLI MARCIA ON THE VIA DI CARCIANO MARCIA CASTELLUM. B. C. 145] THE MARCIA, A GREAT CASTELLUM AQUÆ OR RESERVOIR ON THE VIA DI CARCIANO. This is sometimes called the “Promenade” of Carciano, being a favourite walk on the brow of the hill, from which there is a distant view of S. Peter’s at Rome. This fine reservoir (of which two sides are here shewn) is of the time that this aqueduct was made, B.C. 145. It was probably from this reservoir that a branch _specus_ descended to the Villa of Hadrian below, to which there is a bridle-road from near this point. PLATE X.