There's nothing quite like Tinto Brass's 1979 film, Caligula.
Although at times tastelessly graphic, it is high cinematic expression, showcasing the perversity and bombast of Rome under the rule of mad emperor Gaius Germanicus Caligula, played unforgettably by Malcolm McDowell. Be sure to get a hold of the full-length 160-minute version in all of its pornographic glory. And if you were as hooked on the HBO TV drama "Rome" as we were, "Caligula" will be especially appropriate as "supplemental research." Bonus: Dame Helen Mirren naked.