Well, you can't beat
Gibbon's Decline and Fall of the Roman Empire.It's full of pictures and illustrations, and deals with the time period from Augustus to the fall of the Western Empire.
Only problem is, it is really hard to follow, and not very good for plain facts. It was written 200 years ago, maybe that's why.
Oh, and it's very famous, so it'll make a good conversation piece.But I don't recommend it. You should go to a bookstore, go to the History Section, and browse until you find what you want. Something which is not to difficult to follow, but still gives you enough details.
If you're interested in the Second Punic War, for example, I'm finding the aformentioned book excellent.
The Phoenix