Equality 7-2521 and International 4-8818 find an abandoned tunnel while they are working behind the Theatre. The description of the tunnel leads readers to assume it is constructed from concrete—“it felt like stone, but it was not stone”(14)—and it has steel tracks at the bottom, which suggests that it is an old subway tunnel. These details are among the many clues that a more technologically advanced society once existed in the space now occupied by Equality 7-2521’s benighted world. Whatever this prior society was, all knowledge of it has now been either forgotten or repressed.

Given its importance as a setting, the tunnel comes to symbolize multiple concepts, including Equality 7-2521’s personal rebellion, his individualism, and his mind. The tunnel becomes a symbol of Equality 7-2521’s rebellion when he explores it and urges International 4-8818 to keep it secret. This shared secret subsequently becomes a symbol of the friendship between the two characters. As Equality 7-2521 returns to the tunnel to think, research, and write, it becomes a symbol both of his individualism and his mind. The tunnel represents Equality 7-2521’s mind at the beginning of his enlightenment journey, and it is complemented by light.