|The following is based on Van Buren and has not been confirmed by canon sources.|
Robot City is a mysterious place to the east of Denver, governed by machine intelligences. The robots are attempting to find ODYSSEUS, the Tibbets AI. They are hoping to use ODYSSEUS to correct the "divide" that has occurred within its system - and return the AI to its imprisonment, intended place as their slave.
It is mentioned only in the Tibbets Prison design document.