These public treasures were deposited in the temple of Saturn, on the eastern slope of the Capitoline hill, and, during the republic, were in charge of the urban quaestors (see Quaestor), under the superintendence and control of the senate.
This arrangement continued (except for the year 45 B.C., when no quaestors were chosen) until 28 B.C., when Augustus transferred the aerarium to two praefecti aerarii, chosen annually by the senate from ex-praetors; in 23 these were replaced by two praetors (praetores aerarii or ad aerarium), selected by lot during their term of office; Claudius in A.D.
The origin of the quaestorship is obscure, but it was probably instituted simultaneously with the consulship in 509 B.C. 1 The number of the quaestors was originally two, but this was successively increased to four (in 421 B.C.), eight (in 267 or 241 B.C.), and by Sulla (in 81 B.C.) to twenty.