After a three-year absence, Hercules returns to find his home conquered by the Babylonian empire and his queen enslaved. He must free her before the three rulers of Babylon find her and use her to their own evil purposes. You can find out more about this movie on it's IMDB page .
You can stream Hercules and the Tyrants of Babylon (1964) free and legally on OldReel, via the Internet Archive.
Yes — it is in the public domain and can be watched and shared freely.