I am halfway through Season 2 of "Rome".
I have spent quite a bit of time looking up biographical information on various characters, including Octavian (Augustus Caesar), his mother Atia, his sister and his brother-in-law Agrippa.
Casting surprise: Agrippa is played by Allen Leech, the actor who played Tom Branson, the chauffeur in "Downton Abbey".
"Rome" was an incredibly ambitious and supremely satisfying accomplishment that played loosely with fact about folks, but stayed true to what is known of the times. The production values are astonishing/astounding. If it had not been so expensive to produce, HBO would likely have given it another season or two.
Casting kudos: David Bamber as Cicero. The man is a superb actor. And the late Ray Stevenson as Pullo is wonderful, as well.
I love the entire cast, especially Kevin McKidd as Vorenus. He had an impossibly complex man to portray. Vorenus was a man of morals and loyalty and found himself caught up in the cross hairs of Roman civil unrest. He was astonishing.