Against Apion (Greek: Φλαΐου Ἰωσήπου περὶ ἀρχαιότητος Ἰουδαίων λόγος α and Φλαΐου Ἰωσήπου περὶ ἀρχαιότητος ἀντιρρητικὸς λόγος β; Latin Contra Apionem or In Apionem) is the final work of the Jewish historian Josephus. Originally titled 'Concerning the Antiquity of the Jews', it is a powerful defence of Jewish culture against anti-Semitic critics such as the Alexandrian Greek scholar Apion. It's current title was bestowed by Jerome, who called Josephus 'the Jewish Livy'.
Free Online Texts
Gutenberg: Against Apion. Multiple formats.
Internet Archive: The Complete Works of Flavius Josephus, translated by William Whiston (1737). Multiple formats.
PACE: Against Apion. Greek and English translation by William Whiston. HTML format.
Sacred Texts: The Works of Flavius Josephus, translated by William Whiston. HTML format.
Wikisource: Against Apion: Translated by William Whiston. Online, downloadable via Bookcreator.
Librivox: Minor Works of Josephus - public domain audiobook.
Wikipedia: Against Apion.
The Great Conversation: Further reading at Tom's Learning Notes
Tacitus: The Histories - includes hostile account of the Jewish Revolt that provides significant evidence of the attitude of the contemporary Roman ruling class.
Ancient Greek resources: Learn to read Greek classics in the original.