[182] Commodus was emperor from 180 to 192, but was slain at the early age of 31; and it is probable that this great work was left unfinished, and was completed by his successor, Septimius Severus. In the Regionary Catalogue they are mentioned together, and there was probably no division between them. [183] It was usual to take advantage of the _castella aquæ_ of the great aqueducts to construct bath-chambers of various kinds, both for hot and cold and swimming baths. [184] This is also mentioned in our account of the Anio Vetus (II.), as the branch at the second mile from Rome according to Frontinus. From the low level, it is more probable that this branch came from the Anio Vetus than from the Marcia, and an itinerant pilgrim of the eighth or ninth century may have been mistaken on this point. [185] This was probably the branch that now runs under the Via dei Condotti. The main line to supply the Thermæ of Agrippa has been traced beyond the fountain of Trevi to the Piazza di S. Ignazio, very near the Pantheon, which was the entrance-hall to these _thermæ_. Those of Nero and Alexander Severus were more to the north. [186] See Aqueduct XI. Trajana. [187] HERCVLI . CONSERVATORI INVICTO . COMITI D. N. SEVERI . ALEXANDRI PII . VICTORIS . SEMPER AVG. AC. OPTIMI . PRINCIPIS M. AVRELIVS . PRISCILLIANVS V. C. CVRATOR . NYMPHAEI DEVOT . NVM . M. Q. E. [188] The great Thermæ of the third century in the Esquiliæ, where the building known as the Minerva Medica stands, and to which the other building, called after the Trophies of Marius, is supposed to have been the entrance; this has been identified as a Nymphæum of Alexander Severus, by the representation of it on one of his coins. [189] SOPRA TREBIA (TREVI) VICINO ARCINAZZO (upon Trevi, near Arcinazzo). [190] MINERVAE . MEMORI COELIA . IVLIANA INDVLGENTIA . MEDICI NARVM . INFIRMITATE . EIVS GRAVI . SANATA . D. P [191] There is a subterranean reservoir under it, and there are several other subterranean reservoirs in this ground. [192] This great Pantheum was a temple of all divinities, and also a hall for the men, being connected by a large vaulted passage at the back with the _thermæ_, of both of which there are visible remains. [193] This spring is considered by some authors as the one source of the river Almo; but it is only one of many, and it falls into the deep bed of the river, coming from some miles beyond that point.