Considering Roman art as a cumulative process could help resolve a small iconographical problem. Cubiculum N in the burial hypogeum under the Via Dino Compagni in Rome (c.350–75 ce) features a series of figure scenes referencing the exploits of the mythological hero Hercules. One of these scenes, presently entitled Hercules Slaying an Unknown Enemy, has no direct equivalent in extant Roman art and so has proved difficult to identify. This article suggests that Hercules’ battle with Cacus is most likely the incident referred to here. This is because Antonine medallions and coins, and third-century Roman sarcophagi, use imagery associated with the Cacus story that collectively could have contributed to the design of the Unknown Enemy panel. Further, identifying the defeated enemy as Cacus fits in with, and indeed helps to clarify, programmatic themes and associations already established in the other figure scenes in this funerary chamber.

This article argues that Virgil includes an allusion to the fourth-century censor Appius Claudius Caecus in Book 8 of the Aeneid. Three pieces of evidence point to this allusion: (1) wordplay, especially the near echo of ‘Caecus’ in ‘Cacus’; (2) semantic associations between Cacus and darkness; and (3) repeated references to sight and Cacus’ eyes. By invoking the memory of Appius, whose blinding in 312 b.c.e. allegedly came at the hands of Hercules as punishment for transferring control of the god's rites at the Ara Maxima to the state, Virgil underscores the importance of properly observing religious rituals. This aligns with Evander's original intent with the Hercules–Cacus story to prove to Aeneas and the Trojans that the Arcadians’ religious practices are no uana superstitio (8.187).