The American excavations of the interior of the Hephaisteion and its surroundings were published in 1941. We reexamine the findings, the evidence for the foundations, the original notebooks, and the previously unpublished context pottery, and conclude that the Temple of Hephaistos and Athena was constructed in two stages: the foundations were laid ca. 480 BCE, and after a hiatus the superstructure was completed ca. 465–460 BCE, with repairs after the earthquake of 426 BCE. This article provides a new reconstruction of the interior space, finished without a colonnade, and with painted murals instead. The primary feature of the interior was the statue group, cult images of Athena and Hephaistos, made by Alkamenes of Lemnos and installed in 416/5 BCE.