Death Throes of the Roman Republic (Which is now in their paid archive) is an excellent guide to the time of Caesar. About 11 minutes into to episode 1, most people buy into listening to the whole thing:
I'm sad they're not free anymore, but I remember the drive back from the trip while I listened to them better than most of the trip years later. It starts a good bit before Caesar.
The details about how the country transformed due to different stresses is fascinating, and the commentary on Caesars actions and his writings is particularly memorable.