The show's five acres of outdoor "period" sets were the largest standing set in the world to date.
Five seasons were planned out before the first season aired. However, the show was canceled during season 2 because of its enormous production costs. Much of the material for seasons 3 and 4 was used in the final episodes of the second season to wrap up the show. A proposed movie, to close the story lines, never materialized.
Fifty-five local extras were cast as "Roman Legionaries" and sent to a two-week boot camp, living in tents, to train as Roman soldiers. Training included military discipline (waking at 5 a.m., bed by 9 p.m.), marching, swordsmanship, camp building and dismantling, group training, and maneuvers (day and night time training). Bathing was restricted to the local lake, without soap, at night. Forty-three extras completed the boot camp.
The ruins of Pompeii, Herculaneum, and Ostia Antica were used to determine the proper colors of the temples, statues, and streets, plus graffiti and street signage.
The main characters, Lucius Vorenus and Titus Pullo, are named after real-life historical figures. They are mentioned in Caesars' The Gallic war as two close partners with quarrels between them about each others bravery and who is to be promoted Primus Pilus. They are mentioned as explicitly courageous when Marcus Tullius Cicero's brother was besieged. The audacity of Pullo is also noted, similar to the Pullo in the series.