The temple, vowed by dictator Postumius in 499 B.C. during the battle of Lake Regillus, was in 484 dedicated by his son to Castor and Pollux for their divine help. The high podium and three marble Corynthian columns of the east side, remained of the peripteros of the temple with eight frontal columns, belong to the reconstruction of Tiberius in A.D. 6. This is a brilliant example of the classical style of the Augustan age, interpreting Greek forms of orders with delicacy and elegance, but with traditionally Roman podium heigh and temple decoration. Standarts of weights and measures were kept in this temple.