McMurdo City better known as Big City is a future city in Antarctica. Because of global warming, Antarctica in the 28th Century is covered with cities. One of these cities was magnified in size by the backwards clone Bizarro Brainiac as he seeks to do the reverse what Brainiac did by shrinking Kandor.
The regular human trapped inside the city at the time were also magnified in size and now live a permanent giant. They have decided to remain in the city and not to venture elsewhere on the planet in case of causing any damage.
After a hundred years the people are used to living as giants and have know wish to return to the heights of regular humans, who they now refer to as the little people. Like all humans these being also possessed potential of the the Meta-gene. One such youth was Gim Allon who had the power to shrink down to the height of 6 feet, they dubbed him Micro-Lad.