In scholarly literature, one frequently encounters the claim that Artapanus supplies the only reference to the building of the Temple of Onias in the entire extant corpus of Jewish-Hellenistic literature. While this assumption has found acceptance, this article wishes to investigate that claim. While Artapanus indeed incorporated a reference to the building of a temple by Jews in Heliopolis—the same place, where Josephus located the Temple of Onias—it seems, however, that what Artapanus had in mind was not the Jewish Temple of Onias, but the famed Egyptian Temple of Atum-Ra. This insight is supported by passages of ancient Hellenistic writers such as Herodotus and Diodorus Siculus, who, as Artapanus, contain similar references, to which the latter appears to allude. Artapanus’ note may thus be explained by the notion that the piece of information about Jews being responsible for the building of a famous Egyptian temple fulfills an apologetic purpose and served to aggrandize the Jewish presence in the Egyptian Diaspora.