of the arches can be distinctly seen.  The bridge was constructed by Caligula for the purpose of connecting his palace with the Capitol, on the summit of which stood the magnificent Temple of Jupiter, so that, as he said himself, he might be able to converse conveniently with his colleague, the greatest of the gods!  It is probable that it served more than one purpose; that it was used both as an aqueduct and a road for horses and chariots from the Palatine to the Capitol.  Be this as it may, it must have been a stupendous structure, nearly a quarter of a mile long, and about a hundred feet high, striding over the whole diagonal of the Forum, with a double or triple tier of arches, like the remains of the Claudian aqueduct that spans the Campagna.

The immediate vicinity of the Temple of Castor and Pollux is full of interest to the classical student.  To the right of it are the remains of the Regia or Royal Palace, the official residence of the early kings of Rome, and afterwards, during the whole period of the Republic, of the Pontifex Maximus, as the real head of the State as well as the Church.  Numa Pompilius resided here in the hope that, by occupying neutral ground, he might conciliate the Latins of the Palatine and the Sabines of the Capitoline Hills.  It was also the home of Julius Caesar during the greater part of his life, where Calpurnia, his wife, dreamed that the pediment of the house had fallen down, and the sacred weapons in the Sacrarium were stirred by a supernatural power; an omen that was but too truly fulfilled when Caesar went forth to the Forum on the fatal Ides of March, and was carried back a bloody corpse from the Curia of Pompey.  It ceased to become the residence of the Pontifex when Augustus bought the house of Hortensius on the Palatine, and elected to dwell there instead; and was therefore given over to the Vestal Virgins to increase their scanty accommodation.  The Atrium Vestae, or convent of the Vestal Virgins, adjoined the Regia, and behind it, along the lower slope of the Palatine, stretched the sacred grove of Vesta, which seems to have been used as a place of privileged interment for the sisterhood, as a number of gravestones with the names of vestal virgins upon them were found in digging the foundations of the church of Sta.  Maria Liberatrice in the seventeenth century.  The residence of the Pontifex Maximus and of the Vestal Virgins, who were regarded as the highest and holiest personages in the State, gave an air of great respectability to this neighbourhood, and it became in consequence the fashionable quarter of Rome.  Close beside the house of the Vestal Virgins was the far-famed Temple of Vesta, in which they ministered, whose podium or basement, which is a mere circular mound of rough masonry, may be seen on the spot.