ÆRARIUM Vicesimarum, the place where the money arising from the taxes levied from foreign countries was laid up; so called because it most commonly consisted of a twentieth part of the produce.
There are several other treasuries mentioned in history, as the Ærarium Juventutis, Veneris, &c. The temple of Saturn was the public treasury of Rome, either because Saturn first taught the Italians to coin money, or, which is most likely, because this temple was the strongest and most secure, and therefore the fittest place for that purpose.
Ærarium differs from Fiscus, as the first contained the public money, the second that of the prince. The two are, however, sometimes indiscriminately used for each other.