P3R-118 was a desolate planet in the Milky Way galaxy, which held a Stargate and was going through an ice age. The aristocratic elite of this world lived in a Dome City while the working class, which lived beneath the surface, fought to maintain the systems that supported the city.
The workers did not even know the city existed as they were told that they were directly beneath an ice sheet and that the only way to protect themselves was to maintain constant productivity. At least this was until Administrator Calder tried to make SG-1 workers by stamping their memories. SG-1 discovered their memories had been altered and revealed the truth to the other workers. (SG1: "Beneath the Surface")