I’ll admit, I think John Hurt ("I Claudius" - BBC - 1976) was better suited to play Caligula, however Malcolm McDowell manages to be fairly believable as the tyrannical sexual deviant who possessed absolute authority in the Roman Empire for four years. It shouldn't have been unexpected that he developed into the person he did when we first meet the disturbingly grotesque Tiberius (Peter O'Toole) on his island retreat of Capri. He resides there with a group of nymph attendants and "fishes," guided only by a faint sense of morality from his friend Nerva (Sir John Gielgud). After that brief period of indulgence concludes, our antihero takes the throne and begins to share it with his sister Drusilla (Teresa Ann Savoy), with whom he has an overtly incestuous relationship. There’s pressure for him to marry and produce a legitimate heir, so Caesonia (Helen Mirren) appears—a woman eager to bear imperial offspring while enjoying a life of luxury and corruption. That's the historical background – which is really just a minor element in this shockingly written soft-porn film we are now about to experience in its three-hour entirety. It’s obvious that considerable resources were invested in the film's visual presentation, and director Tinto Brass does provide a rather convincing depiction of the extravagance within a despotic court ruled by a monarch who considered himself divine—and who had few willing to contradict him. Perhaps it is on this point that "Longinus" (John Steiner) takes a firm position. He’s the chancellor who increasingly finds himself, along with Praetorian Commander Chaerea (Paolo Bonacelli), becoming more and more repulsed by the actions of this man with a tenuous grip on reality. Nudity is prevalent throughout to the point where it becomes commonplace, and once you've adjusted to that, the rest of the film fails to capitalize on what could have been an ideal opportunity to portray the height of historical decadence. Instead, we get McDowell acting enthusiastically as he struts around, barely clothed, but little else. It’s cheap—there’s no other way to put it—and the unwelcome intermission completely disrupted any momentum there was as it plodded along in a rather awkward episodic style towards an ending that history documented nearly two thousand years ago. It seems unsure whether it's intended to be a movie or a series of short theatrical pieces; Mirren contributes nothing significant, and the wonderfully repulsive O’Toole isn’t around long enough to make much of an impact. The final product is certainly chaotic, and its length is excessive—but somehow it remains watchable. You might never look at cottage cheese the same way again!

Source on TMDB