The sixth book: #6 The Golden Ass
When ordered by writing date, this book should be listed before anything else I've read so far, but as this is ordered by published date, it comes in later.
The Golden Ass, or the Metamorphoses of Apuleius, tells the story about a man who gets turned into a donkey. He gets better at the end (in a somewhat inconsistent final chapter that becomes more of a religious text, teaching of the greatness of these cults. Before that it's quite an amusing tale, showing the follies of human while also showing up the main character, his selfishness and foibles.
While an interesting story, what felt just as fascinating were the details of Roman life. You hear about a lot of these things in textbooks, but in this novel they are put far more into a real life context, having a normal life punctuated by these oddities, from slaves to how leaders act. The many references to gods - Hercules a favourite, is quite insightful as well, especially where they reference deities that you don't normally think of as a major Roman one.