About 2/3rds of the way through the third book. As audio. Then I got hit by a car and I seriously lost interest. Shit be dry. And mostly you learn that every civilization you've ever heard of, every culture you've ever studied, every people you've ever seen a class presentation on, A) hated women B) tortured the lower class C) is memorable primarily for being incredibly evil. Also, the Stoics were dicks. So was Confucius. But fuckin' Schliemann was a badass.
I love the style of the book set in that picture. I'm sorry to hear it's both dry and depressing, because it does look like a very compelling read. I'd say keep at it. Maybe somewhere, probably around The Renaissance or The Age of Reason, you'll find a bright spot. Though I doubt it will be with Voltaire. I've been told that while he eloquently supported some very revolutionary ideas for his time, he was also crazy racist too.