Alternate names: Temple of Castor and Pollux, Aedes Castoris, Templum Castoris, Aedes Castoris et Pollucis
The temple for Castor and Pollux was built on the southern side of the Forum at the intersection of the Vicus Tuscus. The choice of site is significant: it is near the spring of Juturna, where the heroes were reportedly seen watering their horses after helping the Romans at the battle of Lake Regillus (499/6 BC). The building, first vowed in 484 BC by the dictator, Postumius, went through various phases, starting from the early fifth century BC. The last major remodeling occurred in 6 AD under Tiberius, who dedicated it in his name and that of his deceased brother, Drusus (cf. the Temple of Concordia). Thereafter, Caligula made it the vestibule to his palace. Claudius restored its use as a temple. Much of the podium and three (of 11) columns from the east side of the peripteros survive. The temple (32.1 x 49.5 meters) was built of white Luna marble and its design was peripteral, octostyle, and Corinthian. The cella had interior columns, possibly in giallo antico. The pavement was probably a black and white mosaic. Besides serving as the cult center of Castor and his twin brother Pollux, the podium of the temple also housed the office of weights and measures; and the cella was occasionally the meeting place of Roman Senate. Its front staircase doubled at various times as a rostra that orators addressing crowds in the Forum plaza could use. The temple may have been in ruinous condition in the fourth century AD (see I. Nielsen, Lexicon Topographicum Urbis Romae, vol. 1 [Rome 1993] 245).