The sources of it are the springs under the hill on which La Colonna stands. The same water had been used long before, and brought into Rome by the aqueduct (XI.) of Hadrian and Trajan before mentioned. The large reservoir for the water now in use is very near to the remains of the old one of Hadrian. The construction of this aqueduct is very rude and rough, of concrete and rubble-stone only, and this stone consists entirely of old materials; still the large scale of the work, and the height at which the _specus_ is carried upon the arcade, give it a grand effect. At a little distance, the inferior construction is not seen, and this almost modern aqueduct is frequently mistaken by strangers for one of the old ones of the time of the Empire, of which it is only an imitation. It is seen in several of the views of the older aqueducts in the Campagna, especially those at the Torre Fiscale (531, 1028, 1029) and the Porta Furba (68, 1437). Here it crosses the road to Frascati on an arch, with an inscription upon it. In the latter part of its course it is made on the piers of the Claudian arcade, and it enters Rome at the same point, the north-east corner of the gardens of S. Croce. After passing along the north side of them, it is divided into different branches by a reservoir at the angle, close to the south side of the Porta Maggiore (30). The principal stream then passes along upon the Wall of Aurelian (80 A, B, 81), on the same high bank as the earlier aqueducts had done; it was cut through in making the railway, but a new bridge over that road was built for it (29). Near this it can be seen that it is carried on the piers of an older aqueduct for some distance (28). See Alexandrina (XV.)