The Spacemen City was a domed metropolis located on the Spacemen Homeworld. It was the location of a military complex located in that city where a scientific experiment was underway to give the Spacemen the means to invade the Earth. In the 1950s, Superboy and Krypto arrived in this city to rescue an astronaut that had been abducted by these aliens, and it was him that was being experimented on, as they were using their Energy Transference Device to steal his human energy, so as to make it possible for them to survive in Earth's atmosphere.