We are told that Nero made a Gymnasium and Naumachia in connection with his great palace, or golden house, and no vestiges of any such buildings have been found[45], unless both were combined in the great building called the Colosseum from its colossal size. The amphitheatre at Capua, being also a very large one, is said to have been called a Colosseum, but on rather doubtful authority. It is, however, certain that the name had nothing to do with the Colossus of Nero. It is evident that Nero made a great reservoir of water on this spot, which was supplied from his aqueduct on the Cœlian[46]. The _specus_, or channel for this water, remains in the wall of the Claudium, on the northern side, opposite the Palatine; and at the north-east corner of that part of the Cœlian Hill on which the Claudium stood, are remains of a _piscina_ of the time of Nero, obviously intended for the filtering-place before the water went across into the Colosseum. At a short interval only, about a hundred yards to the south of this, is another _piscina_ of the time of Alexander Severus, when the upper storey was added, and the whole building repaired after the great fire. It is quite possible that Nero made a large oval reservoir on this spot, adjoining to his palace, supplied by an aqueduct, similar to the great oval reservoir on the Palatine, near the house of Augustus, excavated in 1872. The Romans were fond of the oval form for a sheet of water; the basin of the fountain of Domitian, also on the Palatine, is oval; and the remains of the fountain of Juturna in the Forum Romanum shew the same form[47]. The long canals for the vessels to float in, which are ten feet deep, about the same width, and the same height above the original pavements, are not so early as the time of Nero; they are of the third century, with many later repairs.