AERARIUM, the public Treasury of a State or People. See Treasury.

The Temple of Saturn at Rome, being the great Treasury of the city, was first called Aerarium, from Aes, Brass; that being the only Money in use before the Year of Rome 485. Pliny, L. II. c, 33. See Money.

The Aerarium Militare was a Fund of Money, destined for the Maintenance of several Companies of Soldiers, to be in readiness for the better Defense of the City. It was first erected under Augustus, and maintained by a yearly voluntary Contribution; but that proving insufficient, the twentieth Part of all Legacies and Inheritances, except of such as fell to the next of kin or the Poor, were consigned to this Treasury.For the custody thereof, three of his Lifeguard were constituted Praefecti Aerarii. See Praefectus.