Eleven survivors of that great war created a shelter 112.37 miles below the surface. This vault was constructed of material harder and stronger than anything CommanderSpock had measured at that time; its atmosphere (perhaps arranged especially for the landing party) was "a fraction richer in oxygen than usual".
Originally humanoid, the eleven surviving specimens of Sargon's species placed the essence of their minds into spheroid receptacles. In 2268, only two spheres besides Sargon's still contained a living mind: that of Thalassa, Sargon's wife, among the five spheres kept on the lower tier, and that of Henoch, a member of the conflict's "other side", on the upper. (TOS: "Return to Tomorrow")