Aerarium, from aes + -ārium, was the name given in Ancient Rome to the public treasury, and in a secondary sense to the public finances.
The Aerarium Saturni (top) and its ruins (bottom); drawing by Jan Goeree, before 1704
Denarius minted by Gnaeus Nerius, who was urban quaestor in 49 BC. The obverse depicts Saturn, in whose temple the aerarium and the standards of the legions were kept. The reverse shows an aquila between two standards, inscribed H for Hastati and P for Principes, and the names of the consuls.
A treasury is eitherA government department related to finance and taxation, a finance ministry; in a business context, corporate treasury.
A place or location where treasure, such as currency or precious items are kept. These can be state or royal property, church treasure or in private ownership.
The Treasury Building of Brisbane
The Treasury of Athens at Delphi, built with the spoils of the Battle of Marathon