aerarium

Aerarium is a Latin term meaning treasury. In ancient Rome, it referred to the public treasury overseen by the Senate, traditionally housed in the Temple of Saturn in the Forum Romanum. It functioned as the central repository for state funds and revenue and financed public administration, games, religious observances, public works, and military pay with senatorial authorization.

During the Republic, the aerarium held funds derived from taxation and other public revenues, and it was administered by quaestors assigned to manage the treasury under Senate oversight. Expenditures required approval by the Senate or its financial committees, and the aerarium's resources supported the functioning of the state, including the administration, infrastructure, and the salaries of civil servants.

Distinction from the fiscus: the fiscus was the emperor’s treasury, controlled by the imperial administration. The aerarium remained the Senate’s treasury, but over time the lines between these financial systems could blur, especially as imperial power expanded. In late antiquity, the practical separation between state and imperial finances diminished as the empire centralized finances under the ruler.

Aerarium militare: a separate military treasury established in the early Empire to fund veterans’ pensions and related military expenses. Its revenues were drawn from imperial sources and were dedicated to sustaining the army, reflecting the growing specialization of Roman financial administration.

Usage and legacy: the term appears in classical authors to denote the state treasury and, by extension, public funds more generally. Today, aerarium is primarily of historical and linguistic interest, illustrating the dual structure of Roman imperial finances and the Senate’s administrative authority in fiscal matters.