it was supposed to a "mini series" but it was also supposed to last longer than two seasons...
Rome Season 3 Cancelled
It’s been known for a while now, Rome, another superb HBO show has been cancelled and will end after only 2 seasons. Main reasons: lack of viewers and too expensive.
Granted, Rome was originally intended as a mere miniseries but spawned into a full series after the network saw the quality of the scripts. Unfortunately for HBO and any other network, viewer numbers are everything, esp. when the cost for the entire first season is around 100 million U$. We cannot really blame HBO when the viewers rather prefer crap over intelligent, quality TV series. If more people would have watched shows like Rome, Deadwood, Firefly, Invasion they would not have been cancelled, easy as that. Networks need to make profit and have to provide what the majority wants to see and if the majority wants to see crap then they have to give them crap. Besides, what network are you looking for when you want to watch quality shows? HBO, right?
Rome will end on March 25th 2007.
http://www.ihad.de/2007/02/24/rome-season-3-cancelled/