“Of these [Aquæ], six within the seventh mile, on the Via Latina, are taken up into covered _piscinæ_, where, as though breathing again after their course, they deposit mud. The Julia, the Marcia, and the Tepula, are joined there; of these, the Tepula, (which had been intercepted, and joined to the stream of the Julia,) now receives from the reservoir of the same Julia its proper quantity, and flows out in its own channel, and under its own name. “These three are carried from the reservoirs on the same arcade. “The highest of them is the Julia, lower the Tepula, then the Marcia. These come down towards the Viminal, running together beneath the ground, on the same level as the Collis Viminalis, as far as the gate. There they again emerge. “First, however, a part of the Julia is, at the _Spes Vetus_, taken out and distributed in the _castella_ on the Cœlian Hill; but the Marcia, after the Pallantian Gardens, throws off part of its water into a stream called the Herculanean. This conduit through the Cœlian, being of no use for the houses on the hill because at too low a level, comes to an end above the Porta Capena[76].” THE PISCINÆ. To this point, Frontinus tells us, the three aqueducts tend[77], while from this they are carried on the same arcade into Rome. The ruins of these remain visible. Some of them are situated a little way off the south side of the Via Latina, others on the east side of the Via Appia Nova. Of these, two belonging to the Claudia and Anio Novus are subterranean, and are now only to be distinguished as mounds of earth, looking like tumuli. Others are above ground, near that part of the Via Latina [now the road to Frascati and Tusculum], and close to the _Torre di mezza via_, or half-way house from Rome to Frascati, just beyond the sixth milestone of the modern road. Others are at or near the Villa of the time of Hadrian, called _Sette Bassi_ (which is supposed to be a corruption of Septimius Bassus), near the same point. All of these are between seven and eight miles from the City; they are the chief landmarks in tracing the course of the three aqueducts now to be explained, and each of the three comes from its own separate source. The Marcia, the lowest on the arcade, has its origin at the greatest distance from Rome. The Tepula and Julia have their sources comparatively close to the city. The Marcia takes its rise from the Simbrivine Hills, as far removed beyond Tibur to the east as Tibur is from the city, while the latter two find their way from springs in the volcanic region around the lake of Albano. III. MARCIA.