The film starred Sophia Loren (Lucilla), Stephen Boyd (Livius), Alec Guinness (Marcus Aurelius), James Mason (Timonides), Christopher Plummer (Commodus), Mel Ferrer (Cleander), and Omar Sharif (Sohamus, King of Armenia) with Finlay Currie (Caecina), Anthony Quayle (Verulus), John Ireland (Ballomar), Eric Porter (Julianus), Andrew Keir (Polybius), Douglas Wilmer (Niger) and George Murcell (Victorinus). The film was a financial failure at the box-office. However, it is considered unusually intelligent and thoughtful for a film of the contemporary sword and sandal genre.
The time frame of the film is 180 A.D. to 193 A.D., from the death of the Roman Emperor Marcus Aurelius to that of his son and successor Commodus. The film opens with Marcus Aurelius conducting his war to pacify the Germanic tribes along the Danube frontier. He has just summoned the governors of all the Roman provinces to his camp in order to present to them Gaius Metellus Livius (a fictional character) as his heir and successor. Conspirators, acting independently of Commodus, poison the emperor, leaving Livius with only one choice: to proclaim Commodus as "undoubted Caesar." Livius is also deprived of marrying his love, the emperor's daughter Lucilla, because she is married to King Sohamus of Armenia to cement a peace treaty between him and Rome as a buffer to the hostile Persians (Parthians).
Commodus begins his reign by opposing Marcus Aurelius's policy of peace and freedom, which he characterizes as weakness, and demanding more taxes and tribute from the eastern provinces of Syria and Egypt, driving them to rebellion. Meanwhile Livius pacifies the northern frontier through following Marcus Aurelius's policy of making "human frontiers" for the Roman Empire. He and Timonides, a Greek Christian freedman and friend of Marcus Aurelius, return to Rome along with the conquered German leaders (Ballomar, et al.) with the proposal to Romanize and settle them on abandoned farm land. This proposal is accepted by the Roman Senate, but it sets Livius at odds with Commodus, who all but banishes him to continued duty on the northern frontier. When Commodus is faced with the defection of the eastern provinces and Armenia, he has no one but Livius to turn to. Livius proves to be successful against the eastern rebellion, but he declines following Commodus's demand for brutal retribution. Livius answers Commodus with the demand for either a new Rome or a new Caesar.
Commodus reacts by bribing the city of Rome and the army to side with him against Livius. Commodus's success is apparent when one sees that in the temple of Jupiter the traditional head for the colossal statue is replaced with a likeness of the head of Commodus and in the senate it is proposed to change Rome's name to "the city of Commodus" and the empire's name to "the empire of Commodus." Livius is arrested and is ready to be executed with Lucilla, who had tried to assassinate her brother when Commodus returns Livius's favor to him in proclaiming him undoubted Caesar by challenging him to a gladiatorial combat with the imperial throne as the prize. Livius prevails by killing Commodus and rescuing Lucilla from the flames of execution. Victorinus, who had been bribed by Commodus to deliver Livius's army to him, proclaims Livius Caesar, but Livius declines with the warning that if he were Caesar he would crucify them all (Victorinus, Julianus, Niger, et al.). The film culminates in an auction for the imperial throne. This actually occurred in the accession of Didius Julianus. The narrator sums it up: "This was the beginning of the fall of the Roman Empire. A great civilization is not conquered from without until it has destroyed itself from within."
The death of Marcus Aurelius is portrayed as the result of a conspiracy to poison him, which was rumoured at the time. Commodus's liking for gladiators and for fighting as a gladiator himself is historically accurate: it led to rumours that he was actually the bastard son of a gladiator who had been the lover of Marcus Aurelius's wife Faustina. The film makes use of this as a subplot in making Commodus's gladiatorial trainer and comrade, Verulus (Anthony Quayle), his real father. This impresses upon Commodus that he is a bastard who never should have been emperor. In a fit of madness he commits patricide by killing Verulus. Commodus' sister Lucilla's opposition to his rule is also historical: she was even executed for attempting to assassinate him. Her political marriage to the King of Armenia and her survival of her brother are not historically accurate.
The "Battle of the Four Armies" of loyalist and renegade Roman legions against Armenians and Persians is not a historical event. The Sassanid Persian empire did not currently exist at this time (they are standing in for the historical Parthians).
Toward the end of the film Julianus and other senators are shown attempting to bribe the military into making one of them emperor while Commodus and Livius are fighting below them. This makes use of the historical events three months after Commodus's death (he actually died by poisoning and/or strangulation) when Didius Julianus bribed the Praetorian Guard to proclaim him Emperor, outbidding his rival Claudius Pompeianus - a character not shown in the film, though it was he, not a King of Armenia, who actually married Lucilla.
A number of the film's minor characters approximate historical personages: Commodus's corrupt chamberlain Cleander (represented in the film as a blind man), his courtier Niger (who may be identified with Pescennius Niger a rival claimant with Didius Julianus to the imperial throne), and Livius's comrade Victorinus (probably based on the general of the period named Aufidius Victorinus). Other characters of similar political and social standing appear to be completely fictitious.
It is believed that though the film was highly spectacular and considered intelligently scripted, its failure was partly attributable to what was considered the wooden performance of Stephen Boyd as the loyal general Livius (a fictitious character). In contrast, the performance of Christopher Plummer as the unstable Commodus was considered highly charismatic. As a fledgling motion picture performer—The Fall of the Roman Empire was only his third appearance on film—he began to emerge as a major Hollywood star.
The part of Marcus Aurelius was considered to be well portrayed by Alec Guinness, notably in a long soliloquy that was largely quotations from the emperor's own philosophical work The Meditations. The composer Dimitri Tiomkin said he found it impossible to write any music for this soliloquy.
The film's reconstruction of the Roman Forum at Las Matas near Madrid, at 400 x 230 meters (1312 x 754 feet) holds the record for the largest outdoor film set. The various ancient Rome settings covered 55 acres.
The Fall of the Roman Empire was a costly financial failure for producer Samuel Bronston who, after making such epics as John Paul Jones (1959), King of Kings (1961), El Cid (1961), and 55 Days at Peking (1963) had to stop all business activities. A bankruptcy notice in the New York Times on August 6, 1965 stated the cost of The Fall of the Roman Empire at $18,436,625. He announced his return with a planned epic about Isabella of Spain, but the film was never made.
In later years, Miramax would acquire the US rights to the film. After the founders Bob and Harvey Weinstein split with Miramax parent Disney, they formed the Weinstein Company, who currently owns US rights.
It was envisioned that Charlton Heston would be cast as Livius, but ultimately Stephen Boyd, who played opposite to Heston in Ben-Hur got the part. It had been offered to Kirk Douglas, who turned it down.
Richard Harris was originally cast as Commodus, but he was replaced by Christopher Plummer. Harris would later play the role of Marcus Aurelius in the 2000 film Gladiator, which might be considered a remake of The Fall of the Roman Empire.
Alec Guiness was cast as Emperor Marcus Aurelius, and during the production he became good friends with Sophia Loren. On an evening out Sophia persuaded Alec to dance "The Twist" with her, which he did for the first time in his life. On the flight to Spain Guinness was reading the script of the film when he was accosted by one of its authors. Guinness was asked if he was studying the lines, but he responded that he was rewriting the lines since he did not think much of them.
Sophia Loren, the heroine Lucilla, was the highest paid cast member at $1 million.
A novel based on the film is The Fall of the Roman Empire by Harry Whittington (Fawcett Publications, Inc. & Frederick Muller Ltd., 1964).