The Hephaisteion, the Doric temple of Hephaistos and Athena Ergane, crowning the Kolonos Agoraios hill (Fig.1), at the west side of the Athenian Agora, is the best preserved Doric temple from Antiquity. Despite its Doric order, the sculptural decoration of the Hephaisteion, which was constructed in the middle of the fifth century BC, included two continuous Ionic friezes set over the pronaos of the eastern side and the opisthodomos of the western side. Except for the Hephaisteion Ionic friezes, there are only two other cases preserved in Attica: one from the temple of Poseidon at Sounion and one from the Parthenon on the Acropolis of Athens. However, only the Ionic friezes of the Hephaisteion have the unique advantage of being preserved in their original position on the temple, with only minor damage and alterations, so that their situation and function can be researched in situ. In this paper I examine in depth all the features of the Ionic friezes of the Hephaisteion, their architectural position, their visibility, their iconography, their audience, their function and the intention of their construction. Through my research, I attempt to show that the Ionic friezes on these Doric temples were not simply an artistic innovation of fifth-century BC architectural sculpture that flourished in the wealthy environment of Periklean Athens, but that their architectural order and iconography were used conciously by the city of Athens to transmit pro-Athenian messages and constitute eternal monuments of the Athenian achievements.