Fifth-century BC Athens produced a vast quantity of tetradrachms. These “owls” depict on the obverse the helmeted head of Athena, goddess of war and patron deity of the city, and on the reverse an owl – emblem of the goddess – standing right with its head facing towards the viewer, an olive twig and crescent behind, and the letters AΘE before. The majority of Athenian tetradrachms were struck between 454- 404 BC, around the time of the Peloponnesian War. In addition to funding this conflict, the silver from the Laurion mines, coined into these ubiquitous tetradrachms, was used to fund the massive Periklean building campaigns on the Akropolis. Yet these coins, not merely for domestic use, had been since the early 5th century an important international trade currency, setting the weight standards for countless other coinages. Such broad acceptance of Athenian coinage required the engravers to adopt a certain stylistic conservatism, as foreign merchants might not accept a radically redesigned tetradrachm, and the basic types remained unchanged until the introduction of the New Style issues in 165 BC.
Caption from Classical Numismatic Group