Beyond the basilica are three beautiful columns which belong to a restoration of the _Temple of Castor and Pollux_, dedicated by Postumius, B.C. 484. Here costly sacrifices were always offered in the ides of July, at the anniversary of the battle of the Lake Regillus, after which the Roman knights, richly clothed, crowned with olive, and bearing their trophies, rode past it in military procession, starting from the temple of Mars outside the Porta Capena. The entablature which the three columns support is of great richness, and the whole fragment is considered to be one of the finest existing specimens of the Corinthian order. None of the Roman ruins have given rise to more discussion than this. It has perpetually changed its name. Bunsen and many other authorities considered it to belong to the temple of Minerva Chalcidica; but as it is known that the position of the now discovered Basilica Julia was exactly between the temple of Saturn and that of Castor, and a passage of Ovid describes the latter as being close to the site of the temple of Vesta, which is also ascertained, it seems almost certain now that it belonged to the temple of the Dioscuri. Dion-Cassius mentions that Caligula made this temple a vestibule to his house on the Palatine. Here, on the right, branches off the Via dei Fienili, once the _Vicus Tuscus_, or Etruscan quarter (see Chap. V.), leading to the Circus Maximus. At its entrance was the bronze statue of Vertumnus, the god of Etruria, and patron of the quarter. The long trough-shaped fountain here, at which such picturesque groups of oxen and buffaloes are constantly standing, is a memorial of the _Lake of Juturna_ the sister of Turnus, or as she was sometimes described, the wife of Janus the Sabine war-god. This fountain, for such it must have been, was dried up by Paul V. "At quæ venturas præcedit sexta kalendas, Hac sunt Ledæis templa dicata deis. Fratribus illa deis fratres de gente deorum Circa Juturnæ composuere lacus." _Ovid, Fast._ i. 705.