Arch of Septimius Severus, where it had stood for thirteen or fourteen centuries, to the front of the Capitol; while out of another fragment Raphael carved the well-known statue of Jonah sitting on a whale, to be seen in the Chigi Chapel of Sta. Maria del Popolo, the only piece of sculpture executed by the immortal painter. The Italian Government has entirely excavated the ruins, and thus set at rest the numerous controversies among antiquaries regarding its true name. The temple of Castor and Pollux probably dates as far back as the year 487 before Christ, when the dictator Postumius vowed to build a monument in commemoration of his victory at the great battle of Lake Regillus, with which the mythical history of Rome closes. It recalls the well-known romantic legend of the mysterious interference of the Dioscuri in that memorable struggle which Macaulay has woven into one of the most spirited of his Lays. The temple is supposed to have been erected on the spot where the divine Twins announced the victory to the people in the Forum at the close of the day. About twenty feet from the eastern corner of the temple are slight remains of a shallow oval basin, which has been identified as the lake or fountain of Juturna, the wife of Janus, the Sabine war-god, where the Dioscuri washed their armour and horses from the blood and dust of the fray. It was probably at first a natural spring gushing out of the tufa rock of the Palatine Hill, but being dried up, it became in later times a _lacus_ or basin artificially supplied with water. For long ages afterwards the anniversary of the great battle was celebrated every year on the fifteenth of July by a splendid pageant worthy of the greatness of the empire. The Roman knights, clothed in purple robes, and crowned with olive wreaths, and bearing their trophies, first offered sacrifice in the shrine of Castor and Pollux, and then formed a procession, in which five thousand persons sometimes took part, which filed in front of the temple and marched through the city.